Modified pedv spike protein

ABSTRACT

The present invention relates to a modified porcine epidemic diarrhea virus (PEDV) spike (S) protein. Further, the present invention relates to immunogenic compositions comprising said modified PEDV spike protein and methods for immunizing a subject comprising the administration of said immunogenic composition to a subject.

SEQUENCE LISTING

This application contains a sequence listing in accordance with 37 C.F.R. 1.821-1.825. The sequence listing accompanying this application is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to modified PEDV (porcine epidemic diarrhea virus) spike (S) proteins. The modifications result in improved production methods of PEDV vaccines. Further, vaccines comprising the modified Spike proteins are effective as a vaccine and provide protection against PEDV infection or challenge. Due to the high mortality (up to 100%) in less than 10 day old piglets, the disease is of economic concern, for example to the U.S. swine industry.

Description of the Related Art

The porcine epidemic diarrhea virus is an enveloped, positive-sense single-stranded RNA virus that causes acute diarrhea, vomiting, and dehydration in pigs. In pigs three weeks of age and younger, clinical signs (including acute watery, diarrhea, vomiting, and dehydration) can be seen as soon as 24 hours after PEDV infection leading up to 100% mortality. Further, the gross and histological changes in the gut of animals infected with PEDV can cause gross pathological lesions in the small intestine.

PEDV was first identified in Europe but has become increasingly problematic in many Asian countries, including Korea, China, Japan, the Philippines, and Thailand. Since 2013, PEDV emerged in the U.S. and the economic impact of PEDV infection has already been substantial. Accordingly, there is a continuing need to develop vaccines capable of protecting pigs against disease associated with PEDV. In this regard, in particular vaccines are needed that are effective against emerging PEDV strains which could be administered via a mucosal route (oral or intranasal).

Although only one serotype of PEDV has been reported, phylogenetic studies of the S gene show that PEDV can be genetically separated into 2 groups: genogroup 1 (G1; classical) and genogroup 2 (G2; field epidemic or pandemic). Each of the genogroups can be further divided into subgroups (1a and 1b; 2a and 2b). G1a includes the prototype PEDV strain CV777, vaccine strains, and other cell culture-adapted strains, whereas G1b comprises new variants that were first identified in China and later in the United States, South Korea and Europe. G2 comprises global field isolates, which are further clustered into 2a and 2b subgroups (G2a and G2b) responsible for previous local epidemic outbreaks in Asia and recent pandemic outbreaks in North America and Asia, respectively.

PEDV is a member of the subfamily Coronavirinae of genus Alphacoronavirus. PEDV is an enveloped virus possessing approximately a 28 kb, positive-sense, single stranded RNA genome, with a 5′ cap and a 3′ polyadenylated tail. (Pensaert and De Bouck P. 1978). The genome comprises a 5′ untranslated region (UTR), a 3′ UTR, and at least seven open reading frames (ORFs) that encode four structural proteins (spike (S), envelope (E), membrane (M), and nucleocapsid (N)) and three non-structural proteins (replicases 1a and 1b and ORF3); these are arranged on the genome in the order 5′-replicase (1a/1b)-S-ORF3-E-M-N-3′ (Oldham J. 1972; and Bridgen et al. 1993).

The PEDV S protein is a type I glycoprotein, wherein the S protein (of G2b PEDV) is composed of 1,383 amino acids (aa). The S protein can be divided into S1 (e.g., 1-789 aa) and S2 (e.g., 790-1,383 aa) domains based on its homology with S protein of other coronaviruses. The S protein in coronaviruses is a surface antigen, where it plays a role in regulating interactions with host cell receptor glycoproteins to mediate viral entry, and stimulating induction of neutralizing antibodies in the natural host. Thus, the S glycoprotein is a primary target for the development of effective vaccines against PEDV.

Madu et al 2009 (J. Virol.; 83 (15), p. 7411-7421) describe two single mutations (L803A or L804A) in the spike protein of SARS (severe acute respiratory syndrome) and show that each of the single mutations has an impact on membrane fusion activity. Further, Ujike & Taguchi 2015 (Viruses; 7, 1700-1725) describe that mutation of the tyrosine dependent YXXI signal exhibited enhanced cell surface expression. Shirato et al 2011 (Virus Res.; 161 (2):188-93) describe that the mutation H1381R in the KxHxx motif of PEDV results in a transport of the spike protein to the plasma membrane. However, none of said documents disclose that any modifications within the spike protein could improve the production methods of PEDV vaccines and that such produced vaccines with the modifications within the spike protein would still be suitable as a vaccine and provide protection against PEDV infection or challenge.

The solution to the above technical problem is achieved by the description and the embodiments characterized in the claims.

Thus, the invention in its different aspects is implemented according to the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Cellular localization of target proteins (PEDV-S2b-wt and PEDV-S2b-mut) in RK13 cells. Three upper panels demonstrate the expression of spike protein launched from EHV1-PEDV-S2b-wt recombinant vector primarily localized in the cytoplasm, while as shown in the three lower panels, PEDV-S expressed from EHV1-PEDV-S2b-mut localized primarily within the cellular membrane.

FIG. 2. Comparison of the growth of the vectors described in Example 3 (CDV-PEDV-spike-MUT (=CDV-PEDV-spike mut) and CDV-PEDV-spike-WT (=CDV-PEDV-spike WT)) in Vero cells, wherein the upper curve relates to CDV-PEDV-spike mut, and the lower curve relates to CDV-PEDV-spike WT.

DETAILED DESCRIPTION OF THE INVENTION

Before the aspects of the present invention are described, it must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “an antigen” includes a plurality of antigens, reference to the “virus” is a reference to one or more viruses and equivalents thereof known to those skilled in the art, and so forth. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods, devices, and materials are now described. All publications mentioned herein are incorporated herein by reference for the purpose of describing and disclosing the cell lines, vectors, and methodologies as reported in the publications which might be used in connection with the invention. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention.

The invention is based on the surprising finding that mutations in the amino acid sequence of PEDV spike protein are sufficient to increase the production levels of the vector based PEDV vaccines. Further, animal studies have shown that PEDV vector based vaccines having such a modified spike protein are effective and provide or enable protection against PEDV infection or challenge. Thus, the present invention solves the problems inherent in the prior art and provides a distinct advance in the state of the art.

In this regard, the present invention provides a nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein comprising the amino acid sequence

(SEQ ID NO: 1) RSX₁IEDX ₂ X ₃,

wherein

(I) X₂ is an amino acid residue other than a leucine residue and X₃ is a leucine residue, or

(II) X₂ is a leucine residue and X₃ is an amino acid residue other than a leucine residue, or

(III) X₂ is an amino acid residue other than a leucine residue and X₃ is an amino acid residue other than a leucine residue.

In particular, R of the sequence RSX₁IEDX₂X₃ (SEQ ID NO:1, and also of any of the sequences SEQ ID NOS: 4, 5, 21-25 and 31-35, is the conserved arginine residue located in C-terminal direction of the S1/S2 cleavage site. Said R is also termed “the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein” hereinafter. More particular, said R is the arginine residue N-terminally flanking the fusion peptide of said PEDV S protein. The sequence of said fusion peptide generally starts with the sequence SXIED. In particular, said fusion peptide is within the S2 subunit of the PEDV S protein.

The sequence RSX₁IEDX₂X₃ (SEQ ID NO:1) is thus also particularly understood to be a sequence of the fusion domain of said PEDV S protein.

More particularly, in the context of the sequence RSX₁IEDX₂X₃ (SEQ ID NO:1), and also of any of the sequences SEQ ID NOs: 4, 5, 21-25 and 31-35, R relates to the conserved arginine residue at amino acid position 894 if the PEDV S protein is a genotype 2a (G2a) PEDV S protein, or relates to the conserved arginine residue at amino acid position 891 if the PEDV S protein is a genotype 2b (G2b) PEDV S protein. Thus, with regard to the amino acid position, the statement “R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein” is understood to be equivalent to “R is the arginine residue at amino acid position 894 if the PEDV S protein is a genotype 2a (G2a) PEDV S protein, and wherein the numbering of the amino acid position refers to the amino acid sequence of wild type G2a PEDV S protein, preferably of SEQ ID NO:2 or SEQ ID NO:39, or R is the arginine residue at amino acid position 891 if the PEDV S protein is a genotype 2b (G2b) PEDV S protein and wherein the numbering of the amino acid position refers to the amino acid sequence of wild type G2a PEDV S protein, preferably of SEQ ID NO:3”.

Generally, the present invention provides a nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein comprising the amino acid sequence

(SEQ ID NO: 1) RSX₁IEDX ₂ X ₃,

wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein, X₁ can be any amino acid residue, and wherein

(I) X₂ is an amino acid residue other than a leucine residue and X₃ is a leucine residue, or

(II) X₂ is a leucine residue and X₃ is an amino acid residue other than a leucine residue, or

(III) X₂ is an amino acid residue other than a leucine residue and X₃ is an amino acid residue other than a leucine residue.

The term “nucleic acid molecule” refers to polynucleotides including DNA molecules, RNA molecules, cDNA molecules or derivatives. The term encompasses single as well as double stranded polynucleotides. Preferably, the term refers to single stranded RNA or double stranded cDNA. The nucleic acid of the present invention encompasses isolated polynucleotides (i.e. isolated from its natural context) and genetically modified forms. Moreover, comprised are also chemically modified polynucleotides including naturally occurring modified polynucleotides such as glycosylated or methylated polynucleotides or artificial modified ones such as biotinylated polynucleotides. Further, it is to be understood that the spike proteins as mentioned above may be encoded by a large number of polynucleotides due to the degenerated genetic code. Further, the terms “nucleic acid” and “polynucleotide” are interchangeable and refer to any nucleic acid. The terms “nucleic acid” and “polynucleotide” also specifically include nucleic acids composed of bases other than the five biologically occurring bases (adenine, guanine, thymine, cytosine and uracil).

The term “PEDV” is well known to the person skilled in the art. PEDV stands for porcine epidemic diarrhea virus and is a member of the subfamily Coronavirinae of the genus Alphacoronavirus.

The term “spike” refers to a specific protein of the PEDV that is well known by the person skilled in the art. The spike protein is the major inducer of antibodies and protective immune response. Further, the spike protein plays a major role in the cell entry program of PEDV by binding cellular receptors of the host cell and also by mediating virus-cell membrane fusion with the host cell. Further, it is understood that the term “PEDV S protein” is equivalent to the abbreviated term “PEDV S”, which is frequently used in the context of PEDV.

The term “protein”, “amino acid” and “polypeptide” are used interchangeable. The term “protein” refers to a sequence of amino acids (aa) composed of the natural occurring amino acids as well as derivatives thereof. The naturally occurring amino acids or genetically encoded amino acid residues, respectively, are well known in the art and are described in standard text books of biochemistry. Within the amino acid sequence the amino acids are connected by peptide bonds. Further, the two ends of the amino acid sequence are referred to as the carboxyl terminus (C-terminus) and the amino terminus (N-terminus). The term “protein” encompasses essentially purified proteins or protein preparations comprising other proteins in addition. Further, the term also relates to protein fragments. Moreover, it includes chemically modified proteins. Such modifications may be artificial modifications or naturally occurring modifications such as phosphorylation, glycosylation, myristoylation and the like.

100241 In the context of the present invention, the wording “R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein” is understood be equivalent to “R is the conserved arginine residue located in C-terminal direction of the S1/S2 cleavage site of said PEDV S protein” or is equivalent to “R is the conserved arginine residue N-terminally flanking the fusion peptide of said PEDV S protein”, respectively. The wording “N-terminally flanking the fusion peptide” is understood to be equivalent to “N-terminally flanking the fusion peptide sequence”.

The sequence RSX₁IEDX₂X₃ (SEQ ID NO:1) is to be understood as follows:

R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein,

S is the amino acid residue serine,

X₁ is any of the 20 genetically encoded amino acid residues,

I is an isoleucine residue,

E is a glutamate residue,

D is an aspartate residue,

X₂ is a variable. X₂ has two conditions. X₂ can be an amino acid residue other than a leucine (condition 1) which means that X₂ can be any of the genetically encoded amino acid residues besides a leucine residue. Alternatively, X₂ can be a leucine residue (condition 2),

X₃ is a variable. X₃ has two conditions. X₃ can be an amino acid residue other than a leucine residue (condition 1) which means that X₃ can be any of the genetically encoded amino acid residues besides leucine. Alternatively, X₃ can be a leucine residue (condition 2).

Thus, the present invention provides a nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein comprising:

a) the amino acid sequence RSX₁IEDLX₂ (SEQ ID NO:21), and wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein, X₁ can be any amino acid residue, X₂ is an amino acid residue other than a leucine residue, or

b) the amino acid sequence RSX₁IEDX₂L (SEQ ID NO:22), and wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein, X₁ can be any amino acid residue, X₂ is an amino acid residue other than a leucine residue, or

c) the amino acid sequence RSX₁IEDX₂X₃ (SEQ ID NO:1), and wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein, X₁ can be any amino acid residue, X₂ and X₃ are amino acid residues other than leucine residues.

Preferably, the present invention provides a nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein comprising:

a) the amino acid sequence RSXIEDLA (SEQ ID NO:23), and wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein and X can be any amino acid residue, or

b) the amino acid sequence RSXIEDAL (SEQ ID NO:24), and wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein and X can be any amino acid residue, or

c) the amino acid sequence RSXIEDAA (SEQ ID NO:25), and wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein and X can be any amino acid residue.

The term “genetically encoded amino acid residue”, as described in the context of the present invention, in particular refers to an amino acid residue (single letter code in brackets) selected from the group consisting of alanine residue (A), cysteine residue (C), aspartate residue (D), glutamate residue (E), phenylalanine residue (F), glycine residue (G), histidine residue (H), isoleucine residue (I), lysine residue (K), leucine residue (L), methionine residue (M), asparagine residue (N), proline residue (P), glutamine residue (Q), arginine residue (R), serine residue (S), threonine residue (T), valine residue (V), tryptophan residue (W) and tyrosine residue (Y).

Further, the present invention provides a nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein selected from the group consisting of the following (a) and (b):

(a) a genotype 2a (G2a) PEDV S protein having at least one mutation, wherein

-   -   the leucine residue at amino acid position 900 is substituted by         an amino acid residue other than a leucine residue, and/or     -   the leucine residue at amino acid position 901 is substituted by         an amino acid residue other than a leucine residue,

wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2a PEDV S protein of SEQ ID NO:2 or SEQ ID NO:39.

(b) a genotype 2b (G2b) PEDV S having at least one mutation, wherein

-   -   the leucine residue at amino acid position 897 is substituted by         an amino acid residue other than a leucine residue, and/or     -   the leucine residue at amino acid position 898 is substituted by         an amino acid residue other than a leucine residue,

wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2b PEDV S protein of SEQ ID NO:3.

Thus, the present invention provides a nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein selected from the group consisting of the following (a) and (b):

(a) a genotype 2a (G2a) PEDV S protein having at least one mutation, wherein

-   -   the leucine residue at amino acid position 900 is substituted by         an amino acid residue other than a leucine residue and the         residue at amino acid position 901 is a leucine residue, or     -   the residue at amino acid position 900 is a leucine residue and         the residue at amino acid position 901 is substituted by an         amino acid residue other than a leucine residue, or     -   the residues at amino acid positions 900 and 901 are substituted         by an amino acid residue other than a leucine residue,

wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2a PEDV S protein of SEQ ID NO:2 or SEQ ID NO:39;

(b) a genotype 2b (G2b) PEDV S having at least mutation, wherein

-   -   the leucine residue at amino acid position 897 is substituted by         an amino acid residue other than a leucine residue and the         residue at amino acid position 898 is a leucine residue, or     -   the residue at amino acid position 897 is a leucine residue and         the leucine residue at amino acid position 898 is substituted by         an amino acid residue other than a leucine residue, or     -   the residues at amino acid positions 897 and 898 are substituted         by an amino acid residue other than a leucine residue,

wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2b PEDV S protein of SEQ ID NO:3.

As described herein, the wording “the residues at amino acid positions 900 and 901 are substituted by an amino acid residue other than a leucine residue” is equivalent to “the residues at amino acid positions 900 and 901 are each substituted by an amino acid residue other than a leucine residue”, and the wording “the residues at amino acid positions 897 and 898 are substituted by an amino acid residue other than a leucine residue” is equivalent to “the residues at amino acid positions 897 and 898 are each substituted by an amino acid residue other than a leucine residue”, respectively.

It is further understood that the term “genogroup” is equivalent to the term “genotype” as frequently used in the literature in the context of PEDV. The terms “genotype 2a (G2a)” and “genotype 2b (G2b)” are well known to the person skilled in the art. By phylogenetic studies of the S gene PEDV can be genetically separated into 2 groups: genogroup 1 (G1; classical) and genogroup 2 (G2; field epidemic or pandemic). Each of the genogroups can be further divided into subgroups (1a and 1b; 2a and 2b). G2 comprises global field isolates, which are further clustered into 2a and 2b subgroups responsible for previous local epidemic outbreaks in Asia and recent pandemic outbreaks in North America and Asia, respectively.

The term “wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2a PEDV S protein of SEQ ID NO:2 or SEQ ID NO:39” and “wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2b PEDV S protein of SEQ ID NO:3” has to be understood that the numbering of amino acid positions refer to the amino acid sequence of full length wild type G2a PEDV S protein (SEQ ID NO:2 or SEQ ID NO:39) and wild type G2b PEDV S protein (SEQ ID NO:3), respectively. Hence, the numbering of the amino positions as mentioned herein is with reference to a wild type G2a PEDV S protein and wild type G2b PEDV S protein sequence having 1388 or 1386, respectively, or 1383 amino acid residues, including a methionine residue at the (N-terminal) amino acid position 1. Thus, the numbering, as used in the context of the present invention, relates to the sequence of a naturally occurring G2a PEDV S protein and wild type G2b PEDV S protein, as set forth in SEQ ID NO:2 or SEQ ID NO:39, respectively, and SEQ ID NO:3. In other words, if reference is made exemplary to the amino acid or residue at position 900, the amino acid residue is meant which corresponds to amino acid 900 of SEQ ID NO:2 or SEQ ID NO:39, respectively. However, this does not mean that the spike proteins according to the invention have the identical amino acid sequence with SEQ ID NO:2 or SEQ ID NO:39, respectively. It only says, that the corresponding amino acids of the spike protein according to the inventions code for the amino acid residue, as explicitly mentioned.

In another specific aspect of the nucleic acid molecule according to the present invention said amino acid residue other than a leucine residue is selected from the group consisting of alanine residue, glycine residue, isoleucine residue, methionine residue and valine residue.

In another specific aspect of the nucleic acid molecule according to the present invention said amino acid residue other than a leucine residue is selected from the group consisting of alanine residue or glycine residue. Thus, the present invention in particular provides a nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein comprising:

a) the amino acid sequence (SEQ ID NO: 23) RSXIEDLA, or b) the amino acid sequence (SEQ ID NO: 24) RSXIEDAL, or c) the amino acid sequence (SEQ ID NO: 25) RSXIEDAA, or d) the amino acid sequence (SEQ ID NO: 31) RSXIEDLG, or e) the amino acid sequence (SEQ ID NO: 32) RSXIEDGL, or f) the amino acid sequence (SEQ ID NO: 33) RSXIEDGG, or g) the amino acid sequence (SEQ ID NO: 34) RSXIEDGA, or h) the amino acid sequence (SEQ ID NO: 35) RSXIEDAG, and wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein and X can be any amino acid residue.

In another specific aspect of the nucleic acid molecule according to the present invention said amino acid residue other than a leucine residue is an alanine residue.

In another specific aspect of the nucleic acid molecule according to the present invention the numbering of the amino acid positions refers to the amino acid sequence RSXIEDLLF (SEQ ID NO:4) of wild type G PEDV S protein, wherein R is the conserved arginine residue of the S1/S2 cleavage site and LL are the amino acid positions 900 and 901 within the genotype 2a (G2a) PEDV S or LL are the amino acid positions 897 and 898 within the genotype 2b (G2b) PEDV S.

In another specific aspect of the nucleic acid molecule according to the present invention said PEDV S protein comprises the amino acid sequence RSXIEDAAF (SEQ ID NO:5), wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein and AA are the amino acid positions 900 and 901 within the genotype 2a (G2a) PEDV S or AA are the amino acid positions 897 and 898 within the genotype 2b (G2b) PEDV S.

In another specific aspect of the nucleic acid molecule according to the present invention said PEDV S protein further comprises the amino acid sequence

(SEQ ID NO: 6) X ₁X₂X₃FX₄KX₅ X ₆X₇X₈,

wherein X₈ is the C-terminal amino acid residue of said PEDV S protein or the amino acid residue at the -2 position relative to the C-terminal amino acid position of said PEDV S protein,

X₂ to X₅, X₇ and X₈ can be any amino acid residue,

and wherein

(i) X₁ is an amino acid residue other than a tyrosine residue and X₆ is a histidine residue, or

(ii) X₁ is a tyrosine residue and X₆ is an amino acid residue other than a histidine residue, or

(iii) X₁ is an amino acid residue other than a tyrosine residue and X₆ is an amino acid residue other than a histidine residue.

Preferably, in the context of the present invention, X₈ is the C-terminal amino acid residue of said PEDV S protein if said PEDV S protein is a genotype 2b (G2b) PEDV S protein, or X₈ is the amino acid residue at the -2 position relative to the C-terminal amino acid position of said PEDV S protein if said PEDV S protein is a genotype 2a (G2a) PEDV S protein. The term “amino acid residue at the −2 position relative to the C-terminal amino acid position of said PEDV S protein” is understood to be in particular equivalent to” amino acid residue at the amino acid position n-2, wherein n is the amino acid position of the C-terminal amino acid residue of said PEDV S protein”. Thus, for instance, if a PEDV protein, such as a genotype 2a (G2a) PEDV S protein, has an amino acid sequence being 1388 amino acid residues in length, then the amino acid residue at the −2 position relative to the C-terminal amino acid position of said PEDV S protein is the amino acid residue at the amino acid position 1386 of said PEDV protein, or of said genotype 2a (G2a) PEDV S protein, respectively. Further, as described herein, it is in particular understood that the wording “X₂ to X₅, X₇ and X₈ can be any amino acid residue” is equivalent to “each of X₂ to X₅, X₇ and X₈ can be any amino acid residue”. Also, it is in particular understood that the wording “X₂, X₃, X₄, X₅, X₆, X₇ can be any amino acid residue” is equivalent to “each of X₂, X₃, X₄, X₅, X₆ and X₇ can be any amino acid residue”, “X₁, X₂, X₃, X₄, X₆, X₇ can be any amino acid residue” is equivalent to “each of X₁, X₂, X₃, X₄, X₆ and X₇ can be any amino acid residue”, and “X₂, X₃, X₄, X₅, X₇, X₈ can be any amino acid residue” is equivalent to “each of X₂, X₃, X₄, X₅, X₇ and X₈ can be any amino acid residue”, respectively.

Advantageously, said modification within the retention signal of the spike protein to X₁X₂X₃FX₄KX₅X₆X₇X₈ (SEQ ID NO:6) results in a localization of the spike protein into the plasma membrane.

Furthermore, these modifications improve the production methods of PEDV vaccines. This particularly refers to the stability of the recombinant vectors and in addition may allow the recombinant vector to grow with higher titers in the production cell line due to preventing of biological activities of PEDV spike protein through described mutations.

Further, the present invention provides a nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein comprising the amino acid sequence

(SEQ ID NO: 6) X ₁X₂X₃FX₄KX₅ X ₆X₇X₈,

wherein X₈ is the C-terminal amino acid residue of said PEDV S protein or the amino acid residue at the −2 position relative to the C-terminal amino acid position of said PEDV S protein,

X₂ to X₅, X₇ and X₈ can be any amino acid residue, and wherein

(i) X₁ is an amino acid residue other than a tyrosine residue and X₆ is a histidine residue, or

(ii) X₁ is a tyrosine residue and X₆ is an amino acid residue other than a histidine residue, or

(iii) X₁ is an amino acid residue other than a tyrosine residue and X₆ is an amino acid residue other than a histidine residue,

and wherein preferably X₇ is

-   -   the C-terminal amino acid residue of said PEDV S protein if said         PEDV S protein is a genotype 2b (G2b) PEDV S protein, or     -   the amino acid residue at the -2 position relative to the         C-terminal amino acid position of said PEDV S protein if said         PEDV S protein is a genotype 2a (G2a) PEDV S protein.

In another specific aspect of the nucleic acid molecule according to the present invention said PEDV S protein further comprises:

a) the amino acid sequence X₁X₂X₃FX₄KX₅HX₆X₇ (SEQ ID NO:26), wherein X₇ is the C-terminal amino acid residue of said PEDV S protein or the amino acid residue at the -2 position relative to the C-terminal amino acid position of said PEDV S protein, Xi is an amino acid residue other than a tyrosine residue and X₂, X₃, X₄, X₅, X₆, X₇ can be any amino acid residue,

and wherein preferably X₇ is

-   -   the C-terminal amino acid residue of said PEDV S protein if said         PEDV S protein is a genotype 2b (G2b) PEDV S protein, or     -   the amino acid residue at the −2 position relative to the         C-terminal amino acid position of said PEDV S protein if said         PEDV S protein is a genotype 2a (G2a) PEDV S protein;

or

b) the amino acid sequence YX₁X₂FX₃KX₄X₅X₆X₇ (SEQ ID NO:27), wherein X₇ is the C-terminal amino acid residue of said PEDV S protein or the amino acid residue at the −2 position relative to the C-terminal amino acid position of said PEDV S protein, X₅ is an amino acid residue other than a histidine residue and X₁, X₂, X₃, X₄, X₆, X₇ can be any amino acid residue,

and wherein preferably X₇ is

-   -   the C-terminal amino acid residue of said PEDV S protein if said         PEDV S protein is a genotype 2b (G2b) PEDV S protein, or     -   the amino acid residue at the −2 position relative to the         C-terminal amino acid position of said PEDV S protein if said         PEDV S protein is a genotype 2a (G2a) PEDV S protein;

or

c) the amino acid sequence X₁X₂X₃FX₄KX₅X₆X₇X₈ (SEQ ID NO:6), wherein X₈ is the C-terminal amino acid residue of said PEDV S protein or the amino acid residue at the −2 position relative to the C-terminal amino acid position of said PEDV S protein, X₁ is an amino acid residue other than a tyrosine residue and X₆ is an amino acid residue other than a histidine residue and X₂, X₃, X₄, X₅, X₇, X₈ can be any amino acid residue,

and wherein preferably X₈ is

-   -   the C-terminal amino acid residue of said PEDV S protein if said         PEDV S protein is a genotype 2b (G2b) PEDV S protein, or     -   the amino acid residue at the -2 position relative to the         C-terminal amino acid position of said PEDV S protein if said         PEDV S protein is a genotype 2a (G2a) PEDV S protein.

In another specific aspect of the nucleic acid molecule according to the present invention said PEDV S protein further comprises:

a) the amino acid sequence (SEQ ID NO: 28) AXXFXKXHXX-COOH, or b) the amino acid sequence (SEQ ID NO: 29) YXXFXKXRXX-COOH, or c) the amino acid sequence (SEQ ID NO: 30) AXXFXKXRXX-COOH,

wherein X—COOH is the C-terminal amino acid residue of said PEDV S protein or the amino acid residue at the −2 position relative to the C-terminal amino acid position of said PEDV S protein, and X can be any amino acid residue,

and wherein preferably X—COOH is

-   -   the C-terminal amino acid residue of said PEDV S protein if said         PEDV S protein is a genotype 2b (G2b) PEDV S protein, or     -   the amino acid residue at the −2 position relative to the         C-terminal amino acid position of said PEDV S protein if said         PEDV S protein is a genotype 2a (G2a) PEDV S protein.

In another specific aspect of the nucleic acid molecule according to the present invention,

(a) in said G2a PEDV S protein further

-   -   the tyrosine residue at amino acid position 1377 is substituted         by an amino acid residue other than a tyrosine residue, and/or     -   the histidine residue at amino acid position 1384 is substituted         by amino acid residue other than a histidine residue,

or

(b) in said G2b PEDV S protein further

-   -   the tyrosine residue at amino acid position 1374 is substituted         by an amino acid residue other than a tyrosine residue, and/or     -   the histidine residue at amino acid position 1381 is substituted         by an amino acid residue other than a histidine residue.

As defined above, the numbering, as used in the context of the present invention, relates to the sequence of a naturally occurring G2a PEDV S protein and wild type G2b PEDV S protein, as set forth in SEQ ID NO:2 or SEQ ID NO:39, respectively, and SEQ ID NO:3.

In another specific aspect of the nucleic acid molecule according to the present invention,

(a) in said G2a PEDV S protein further

-   -   the tyrosine residue at amino acid position 1377 is substituted         by an amino acid residue other than a tyrosine residue and the         residue at amino acid position 1384 is a histidine residue, or     -   the amino acid residue at amino acid position 1377 is a tyrosine         residue and the histidine residue at amino acid position 1384 is         substituted by an amino acid residue other than a histidine         residue, or     -   the tyrosine residue at amino acid position 1377 is substituted         by an amino acid residue other than a tyrosine residue and the         histidine residue at amino acid position 1384 is substituted by         an amino acid residue other than a histidine residue,

or

(b) in said G2b PEDV S protein further

-   -   the tyrosine residue at amino acid position 1374 is substituted         by an amino acid residue other than a tyrosine residue and the         residue at amino acid position 1381 is a histidine residue, or     -   the residue at amino acid position 1374 is a tyrosine residue         and the histidine residue at amino acid position 1381 is         substituted by an amino acid residue other than a histidine         residue, or     -   the tyrosine residue at amino acid position 1374 is substituted         by an amino acid residue other than a tyrosine residue and the         histidine residue at amino acid position 1381 is substituted by         an amino acid residue other than a histidine residue.

In another specific aspect of the nucleic acid molecule according to the present invention,

-   -   said amino acid residue other than a tyrosine residue is         selected from the group consisting of alanine residue, glycine         residue, leucine residue, isoleucine residue, methionine residue         and valine residue, and/or     -   said amino acid residue other than a histidine residue is an         arginine residue.

In another specific aspect of the nucleic acid molecule according to the present invention,

-   -   said amino acid residue other than a tyrosine residue is an         alanine residue, and/or     -   said amino acid residue other than a histidine residue is an         arginine residue.

In another specific aspect of the nucleic acid molecule according to the present invention the numbering of the amino acid positions refers to the amino acid sequence YXXFXKXH (SEQ ID NO:7) of wild type G PEDV S protein, wherein Y and H are the amino acid positions 1377 and 1384 within the genotype 2a (G2a) PEDV S protein or Y and H are the amino acid positions 1374 and 1381 within the genotype 2b (G2b) PEDV S protein.

In another specific aspect of the nucleic acid molecule according to the present invention the nucleic acid molecule comprises a sequence encoding the amino acid sequence AXXFXKXR (SEQ ID NO:8), wherein A and R are the amino acid positions 1377 and 1384 within the genotype 2a (G2a) PEDV S protein or A and R are the amino acid positions 1374 and 1381 within the genotype 2b (G2b) PEDV S protein.

In another specific aspect of the nucleic acid molecule according to the present invention said PEDV S protein:

i) (a) comprises or consists of an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 15, 16, 17, 18, 19, 20, 40, or

(b) comprises or consists of an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 9, 10, 11, 12, 13, 14; and/or

ii) (a) is encoded by a nucleotide sequence encoding an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 15, 16, 17, 18, 19, 20, 40, or

(b) is encoded by a nucleotide sequence encoding an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 9, 10, 11, 12, 13, 14.

The term “identity” or “sequence identity” is known in the art and refers to a relationship between two or more polypeptide sequences or two or more polynucleotide sequences, namely a reference sequence and a given sequence to be compared with the reference sequence. Sequence identity is determined by comparing the given sequence to the reference sequence after the sequences have been optimally aligned to produce the highest degree of sequence similarity, as determined by the match between strings of such sequences. Upon such alignment, sequence identity is ascertained on a position-by-position basis, e.g., the sequences are “identical” at a particular position if at that position, the nucleotides or amino acid residues are identical. The total number of such position identities is then divided by the total number of nucleotides or residues in the reference sequence to give % sequence identity. Sequence identity can be readily calculated by known methods, including but not limited to, those described in Computational Molecular Biology, Lesk, A. N., ed., Oxford University Press, New York (1988), Biocomputing: Informatics and Genome Projects, Smith, D. W., ed., Academic Press, New York (1993); Computer Analysis of Sequence Data, Part I, Griffin, A. M., and Griffin, H. G., eds., Humana Press, New Jersey (1994); Sequence Analysis in Molecular Biology, von Heinge, G., Academic Press (1987); Sequence Analysis Primer, Gribskov, M. and Devereux, J., eds., M. Stockton Press, New York (1991); and Carillo, H., and Lipman, D., SIAM J. Applied Math., 48: 1073 (1988), the teachings of which are incorporated herein by reference. Preferred methods to determine the sequence identity are designed to give the largest match between the sequences tested. Methods to determine sequence identity are codified in publicly available computer programs which determine sequence identity between given sequences. Examples of such programs include, but are not limited to, the GCG program package (Devereux, J., et al., Nucleic Acids Research, 12(1):387 (1984)), BLASTP, BLASTN and FASTA (Altschul, S. F. et al., J. Molec. Biol., 215:403-410 (1990). The BLASTX program is publicly available from NCBI and other sources (BLAST Manual, Altschul, S. et al., NCVI NLM NIH Bethesda, Md. 20894, Altschul, S. F. et al., J. Molec. Biol., 215:403-410 (1990), the teachings of which are incorporated herein by reference). These programs optimally align sequences using default gap weights in order to produce the highest level of sequence identity between the given and reference sequences. As an illustration, by a polynucleotide having a nucleotide sequence having at least, for example, 85%, preferably 90%, even more preferably 95% “sequence identity” to a reference nucleotide sequence, it is intended that the nucleotide sequence of the given polynucleotide is identical to the reference sequence except that the given polynucleotide sequence may include up to 15, preferably up to 10, even more preferably up to 5 point mutations per each 100 nucleotides of the reference nucleotide sequence. In other words, in a polynucleotide having a nucleotide sequence having at least 85%, preferably 90%, even more preferably 95% identity relative to the reference nucleotide sequence, up to 15%, preferably 10%, even more preferably 5% of the nucleotides in the reference sequence may be deleted or substituted with another nucleotide, or a number of nucleotides up to 15%, preferably 10%, even more preferably 5% of the total nucleotides in the reference sequence may be inserted into the reference sequence. These mutations of the reference sequence may occur at the 5′ or 3′ terminal positions of the reference nucleotide sequence or anywhere between those terminal positions, interspersed either individually among nucleotides in the reference sequence or in one or more contiguous groups within the reference sequence. Analogously, by a polypeptide having a given amino acid sequence having at least, for example, 85%, preferably 90%, even more preferably 95% sequence identity to a reference amino acid sequence, it is intended that the given amino acid sequence of the polypeptide is identical to the reference sequence except that the given polypeptide sequence may include up to 15, preferably up to 10, even more preferably up to 5 amino acid alterations per each 100 amino acids of the reference amino acid sequence. In other words, to obtain a given polypeptide sequence having at least 85%, preferably 90%, even more preferably 95% sequence identity with a reference amino acid sequence, up to 15%, preferably up to 10%, even more preferably up to 5% of the amino acid residues in the reference sequence may be deleted or substituted with another amino acid, or a number of amino acids up to 15%, preferably up to 10%, even more preferably up to 5% of the total number of amino acid residues in the reference sequence may be inserted into the reference sequence. These alterations of the reference sequence may occur at the amino or the carboxy terminal positions of the reference amino acid sequence or anywhere between those terminal positions, interspersed either individually among residues in the reference sequence or in the one or more contiguous groups within the reference sequence. Preferably, residue positions which are not identical differ by conservative amino acid substitutions. However, conservative substitutions are not included as a match when determining sequence identity.

The terms “identity”, “sequence identity” and “percent identity” are used interchangeably herein. For the purpose of this invention, it is defined here that in order to determine the percent identity of two amino acid sequences or two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in the sequence of a first amino acid or nucleic acid for optimal alignment with a second amino or nucleic acid sequence). The amino acid or nucleotide residues at corresponding amino acid or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid or nucleotide residue as the corresponding position in the second sequence, then the molecules are identical at that position. The percent identity between the two sequences is a function of the number of identical positions shared by the sequences (i.e., % identity =number of identical positions/total number of positions (i.e. overlapping positions)×100). Preferably, the two sequences are the same length.

A sequence comparison may be carried out over the entire lengths of the two sequences being compared or over fragment of the two sequences. Typically, the comparison will be carried out over the full length of the two sequences being compared. However, sequence identity may be carried out over a region of, for example, twenty, fifty, one hundred or more contiguous amino acid residues.

The skilled person will be aware of the fact that different computer programs are available to determine the homology between two sequences. For instance, a comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm. In a preferred embodiment, the percent identity between two amino acid or nucleic acid sequences is determined using the Needleman and Wunsch (J. Mol. Biol. (48): 444-453 (1970)) algorithm which has been incorporated into the GAP program in the Accelrys GCG software package (available at http://www.accelrys.com/products/gcg/), using either a Blosum 62 matrix or a PAM250 matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or 6. The skilled person will appreciate that all these different parameters will yield slightly different results but that the overall percentage identity of two sequences is not significantly altered when using different algorithms.

The protein sequences or nucleic acid sequences of the present invention can further be used as a “query sequence” to perform a search against public databases to, for example, to identify other family members or related sequences. Such searches can be performed using the BLASTN and BLASTP programs (version 2.0) of Altschul, et al. (1990) J. Mol. Biol. 215:403-10. BLAST protein searches can be performed with the BLASTP program, score=50, wordlength=3 to obtain amino acid sequences homologous to protein molecules of the invention. To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul et al. (1997) Nucleic Acids Res. 25(17): 3389-3402. When utilizing BLAST and Gapped BLAST programs, the default parameters of the respective programs (e.g., BLASTP and BLASTN) can be used. See the homepage of the National Center for Biotechnology Information at http://www.ncbi.nlm.nih.gov/.

As used herein, it is in particular understood that the term “identical to the sequence of SEQ ID NO:Y” is equivalent to the term “identical to the sequence of SEQ ID NO:Y over the length of SEQ ID NO:Y” or to the term “identical to the sequence of SEQ ID NO:Y over the whole length of SEQ ID NO:Y”, respectively. In this context, “Y” is any integer selected from 1 to 40 so that “SEQ ID NO:Y” represents any of the SEQ ID NOs mentioned herein.

100581 In another specific aspect of the nucleic acid molecule according to the present invention said PEDV S protein

(a) comprises the amino acid sequence of any one of SEQ ID NOS: 15, 16, 17, 18, 19, 20, 40, or

(b) comprises the amino acid sequence of any one of SEQ ID NOS: 9, 10, 11, 12, 13, 14.

In an exemplary and non-limiting example the nucleic acid molecule according to the present invention comprises a nucleotide sequence selected from the group consisting of SEQ ID NO:36, SEQ ID NO:37 and SEQ ID NO:38.

Further, the present invention provides a PEDV (S) protein encoded by the nucleic acid molecule as described herein.

In another specific aspect of the nucleic acid molecule or the PEDV S protein according to the present invention said nucleic acid molecule encoding the PEDV S protein or the PEDV S protein is recombinant.

The term “recombinant” as used herein relates to a polynucleotide (including DNA molecules, RNA molecules, cDNA molecules or derivatives) or polypeptide (or protein) having any modifications that do not naturally occur to the corresponding polynucleotide or polypeptide. For instance, a polynucleotide or polypeptide is considered “recombinant” if it contains an insertion, deletion, inversion, relocation or a point mutation introduced artificially, e.g., by human intervention. Therefore, the polynucleotide or polypeptide is not associated with all or a portion of the sequences (polynucleotide or polypeptide) with which it is associated in nature. The term “recombinant” as used with respect to a virus, means a virus produced by artificial manipulation of the viral genome. The term “recombinant virus” encompasses genetically modified viruses.

Preferably, the protein of the present invention is a non-naturally-occurring protein.

Preferably, said protein is an isolated polypeptide.

Further, the present invention provides a polynucleotide comprising the nucleic acid molecule as described herein.

Production of the nucleic acid molecule and polynucleotides described herein is within the skill in the art and can be carried out according to recombinant techniques described, among other places, in Sam brook et al., 2001, Molecular Cloning, A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y.; Amusable, et al., 2003, Current Protocols In Molecular Biology, Greene Publishing Associates & Wiley Interscience, NY; Innis et al. (eds), 1995, PCR Strategies, Academic Press, Inc., San Diego; and Erlich (ed), 1994, PCR Technology, Oxford University Press, New York, all of which are incorporated herein by reference.

Further, the present invention provides a vector comprising the nucleic acid molecule as described herein or the polynucleotide as described herein.

The term “vector” as it is known in the art refers to a polynucleotide construct, typically a plasmid or a bacterial artificial chromosome, used to transmit genetic material to a host cell. Vectors can be, for example, bacteria, viruses, phages, bacterial artificial chromosomes, cosmids, or plasmids. A vector as used herein can be composed of or contain either DNA or RNA. In some embodiments, a vector is composed of DNA. In some embodiments a vector is an infectious virus. Such a viral vector contains a viral genome which was manipulated in a way that it carries a foreign gene which has no function in the replication of the viral vector neither in cell culture nor in a host animal. According to specific aspects of the present disclosure a vector may be used for various aspects such as mere transmission of genetic material, for the transfection of host cells or organisms, for use as vaccines, e.g. DNA vaccines or for gene expression purposes. Gene expression is a term describing the biosynthesis of a protein in a cell as directed by a specific polynucleotide sequence called gene. In a specific aspect a vector may be an “expression vector”, which is a vector that is capable of directing the expression of a protein encoded by one or more genes carried by the vector when it is present in the appropriate environment.

100691 Vectors and methods for making and/or using vectors (or recombinants) for expression can be by or analogous to the methods disclosed in: U.S. Pat. Nos. 4,603,112, 4,769,330, 5,174,993, 5,505,941, 5,338,683, 5,494,807, 4,722,848, 5,942,235, 5,364,773, 5,762,938, 5,770,212, 5,942,235, 382,425, PCT publications WO 94/16716, WO 96/39491, WO 95/30018; Paoletti, “Applications of pox virus vectors to vaccination: An update, “PNAS USA 93: 11349-11353, October 1996; Moss, “Genetically engineered poxviruses for recombinant gene expression, vaccination, and safety,” PNAS USA 93: 11341-11348, October 1996; Smith et al., U.S. Pat. No. 4,745,051(recombinant baculovirus); Richardson, C. D. (Editor), Methods in Molecular Biology 39, “Baculovirus Expression Protocols” (1995 Humana Press Inc.); Smith et al., “Production of Human Beta Interferon in Insect Cells Infected with a Baculovirus Expression Vector”, Molecular and Cellular Biology, December, 1983, Vol. 3, No. 12, p. 2156-2165; Pennock et al., “Strong and Regulated Expression of Escherichia coli B-Galactosidase in Infect Cells with a Baculovirus vector, “Molecular and Cellular Biology March 1984, Vol. 4, No. 3, p. 406; EPAO 370 573; U.S. application No. 920,197, filed Oct. 16, 1986; EP Patent publication No. 265785; U.S. Pat. No. 4,769,331 (recombinant herpesvirus); Roizman, “The function of herpes simplex virus genes: A primer for genetic engineering of novel vectors,” PNAS USA 93:11307-11312, October 1996; Andreansky et al., “The application of genetically engineered herpes simplex viruses to the treatment of experimental brain tumors,” PNAS USA 93: 11313-11318, October 1996; Robertson et al., “Epstein-Barr virus vectors for gene delivery to B lymphocytes”, PNAS USA 93: 11334-11340, October 1996; Frolov et al., “Alphavirus-based expression vectors: Strategies and applications,” PNAS USA 93: 11371-11377, October 1996; Kitson et al., J. Virol. 65, 3068-3075, 1991; U.S. Pat. Nos. 5,591,439, 5,552,143; WO 98/00166; allowed U.S. application Ser. Nos. 08/675,556, and 08/675,566 both filed Jul. 3, 1996 (recombinant adenovirus); Grunhaus et al., 1992, “Adenovirus as cloning vectors,” Seminars in Virology (Vol. 3) p. 237-52, 1993; Ballay et al. EMBO Journal, vol. 4, p. 3861-65, Graham, Tibtech 8, 85-87, April, 1990; Prevec et al., J. Gen Virol. 70, 42434; PCT WO 91/11525; Felgner et al. (1994), J. Biol. Chem. 269, 2550-2561, Science, 259: 1745-49, 1993; and McClements et al., “Immunization with DNA vaccines encoding glycoprotein D or glycoprotein B, alone or in combination, induces protective immunity in animal models of herpes simplex virus-2 disease”, PNAS USA 93: 11414-11420, October 1996; and U.S. Pat. Nos. 5,591,639, 5,589,466, and 5,580,859, as well as WO 90/11092, WO93/19183, WO94/21797, WO95/11307, WO95/20660; Tang et al., Nature, and Furth et al., Analytical Biochemistry, relating to DNA expression vectors, inter alia. See also WO 98/33510; Ju et al., Diabetologia, 41: 736-739, 1998 (lentiviral expression system); Sanford et al., U.S. Pat. No. 4,945,050; Fischbachet al. (Intracel); WO 90/01543; Robinson et al., Seminars in Immunology vol. 9, pp. 271-283 (1997), (DNA vector systems); Szoka et al., U.S. Pat. No. 4,394,448 (method of inserting DNA into living cells); McCormick et al., U.S. Pat. No. 5,677,178 (use of cytopathic viruses); and U.S. Pat. No. 5,928,913 (vectors for gene delivery); as well as other documents cited herein.

Preferably, said vector is a viral vector.

The term “viral vector” describes a genetically modified virus which was manipulated by recombinant DNA technique in a way so that its entry into a host cell results in a specific biological activity, e.g. the expression of a transgene carried by the vector. In a specific aspect the transgene is an antigen. A viral vector may or may not be replication competent in the target cell, tissue, or organism. It is in particular understood, that the term “viral vector”, as used herein, is equivalent to the term “virus vector”.

Generation of a viral vector can be accomplished using any suitable genetic engineering techniques well known in the art, including, without limitation, the standard techniques of restriction endonuclease digestion, ligation, transformation, plasmid purification, DNA sequencing, transfection in cell cultures, for example as described in Sambrook et al. (Molecular Cloning: A Laboratory Manual. Cold Spring Harbor Laboratory Press, N.Y. (1989)) or K. Maramorosch and H. Koprowski (Methods in Virology Volume VIII, Academic Press Inc. London, UK (2014)).

A viral vector can incorporate sequences from the genome of any known organism. The sequences can be incorporated in their native form or can be modified in any way to obtain a desired activity. For example, the sequences can comprise insertions, deletions or substitutions.

In a specific aspect of the vector according to the present invention the vector is a CDV (Canine Distemper Virus), EHV (Equine Herpes Virus) or ORF virus (a parapox virus), PRV (pseudorabies virus), CAV (canine adenovirus), PCMV (porcine cytomegalovirus) or BoHV-4 (bovine herpesvirus-4).

In a specific aspect of the vector according to the present invention the vector is a CDV or EHV.

Further, the present invention provides an immunogenic composition comprising the nucleic acid molecule encoding the PEDV S protein as described herein and/or the PEDV S protein as described herein and/or the vector as described herein.

The term “immunogenic composition” refers to a composition that comprises at least one antigen, which elicits an immunological response in the host to which the immunogenic composition is administered. Such immunological response may be a cellular and/ or antibody-mediated immune response to the immunogenic composition of the invention. Preferably, the immunogenic composition induces an immune response and, more preferably, confers protective immunity against one or more of the clinical signs of a PEDV infection. The host is also described as “subject”. Preferably, any of the hosts or subjects described or mentioned herein is a piglet, pig or sow.

Usually, an “immunological response” includes but is not limited to one or more of the following effects: the production or activation of antibodies, B cells, helper T cells, suppressor T cells, and/or cytotoxic T cells and/or gamma-delta T cells, directed specifically to an antigen or antigens included in the immunogenic composition of the invention. Preferably, the host will display either a protective immunological response or a therapeutically response.

A “protective immunological response” or “protective immunity” will be demonstrated by either a reduction or lack of clinical signs normally displayed by an infected host, a quicker recovery time and/or a lowered duration of infectivity or lowered pathogen titer in the tissues or body fluids or excretions of the infected host.

In case where the host displays a protective immunological response such that resistance to new infection will be enhanced and/or the clinical severity of the disease reduced, the immunogenic composition is described as a “vaccine”.

In another specific aspect of the immunogenic composition according to the present invention the immunogenic composition further comprises a pharmaceutically acceptable carrier.

The term “pharmaceutical-acceptable carrier” includes any and all solvents, dispersion media, coatings, stabilizing agents, diluents, preservatives, antibacterial and antifungal agents, isotonic agents, adsorption delaying agents, adjuvants, immune stimulants, and combinations thereof.

“Diluents” can include water, saline, dextrose, ethanol, glycerol, and the like. Isotonic agents can include sodium chloride, dextrose, mannitol, sorbitol, and lactose, among others. Stabilizers include albumin and alkali salts of ethylendiamintetracetic acid, among others.

In one aspect of the present invention the pharmaceutically acceptable carrier is phosphate buffered saline.

Preferably, the immunogenic composition further comprises sucrose gelatin stabilizer.

In one aspect of the present invention the pharmaceutically acceptable carrier is chitosan.

Chitosan is a natural deacetylated polysaccharide from chitin in crustaceans (e.g., shrimp, crab), insects, and other invertebrates. Recently, Rauw et al. 2009 (Vet Immunol Immunop 134:249-258) demonstrated that chitosan enhanced the cellular immune response of live Newcastle disease vaccine and promoted its protective effect. Further, Wang et al., 2012 (Arch Virol (2012) 157:1451-1461) have shown results revealing the potential of chitosan as an adjuvant for use in a live attenuated influenza vaccine.

Preferably, the immunogenic composition can further include one or more other immunomodulatory agents such as, e.g. interleukins, interferons, or other cytokines. The amounts and concentrations of adjuvants and additives useful in the context of the present invention can readily be determined by the skilled artisan.

In some aspects, the immunogenic composition of the present invention contains an adjuvant. “Adjuvants” as used herein, can include aluminum hydroxide and aluminum phosphate, saponins e.g., Quil A, QS-21 (Cambridge Biotech Inc., Cambridge Mass.), GPI-0100 (Galenica Pharmaceuticals, Inc., Birmingham, Ala.), water-in-oil emulsion, oil-in-water emulsion, water-in-oil-in-water emulsion. The emulsion can be based in particular on light liquid paraffin oil (European Pharmacopea type); isoprenoid oil such as squalane or squalene; oil resulting from the oligomerization of alkenes, in particular of isobutene or decene; esters of acids or of alcohols containing a linear alkyl group, more particularly plant oils, ethyl oleate, propylene glycol di-(caprylate/caprate), glyceryl tri-(caprylate/caprate) or propylene glycol dioleate; esters of branched fatty acids or alcohols, in particular isostearic acid esters. The oil is used in combination with emulsifiers to form the emulsion. The emulsifiers are preferably nonionic surfactants, in particular esters of sorbitan, of mannide (e.g. anhydromannitol oleate), of glycol, of polyglycerol, of propylene glycol and of oleic, isostearic, ricinoleic or hydroxystearic acid, which are optionally ethoxylated, and polyoxypropylene-polyoxyethylene copolymer blocks, in particular the Pluronic products, especially L121. See Hunter et al., The Theory and Practical Application of Adjuvants (Ed.Stewart-Tull, D. E. S.), JohnWiley and Sons, NY, pp51-94 (1995) and Todd et al., Vaccine 15:564-570 (1997). Exemplary adjuvants are the SPT emulsion described on page 147 of “Vaccine Design, The Subunit and Adjuvant Approach” edited by M. Powell and M. Newman, Plenum Press, 1995, and the emulsion MF59 described on page 183 of this same book.

A further instance of an adjuvant is a compound chosen from the polymers of acrylic or methacrylic acid and the copolymers of maleic anhydride and alkenyl derivative. Advantageous adjuvant compounds are the polymers of acrylic or methacrylic acid which are cross-linked, especially with polyalkenyl ethers of sugars or polyalcohols. These compounds are known by the term carbomer (Phameuropa Vol. 8, No. 2, June 1996). Persons skilled in the art can also refer to U.S. Pat. No. 2,909,462 which describes such acrylic polymers cross-linked with a polyhydroxylated compound having at least 3 hydroxyl groups, preferably not more than 8, the hydrogen atoms of at least three hydroxyls being replaced by unsaturated aliphatic radicals having at least 2 carbon atoms. The preferred radicals are those containing from 2 to 4 carbon atoms, e.g. vinyls, allyls and other ethylenically unsaturated groups. The unsaturated radicals may themselves contain other substituents, such as methyl. The products sold under the name Carbopol; (BF Goodrich, Ohio, USA) are particularly appropriate. They are cross-linked with an allyl sucrose or with allyl pentaerythritol. Among then, there may be mentioned Carbopol 974P, 934P and 971P. Most preferred is the use of Carbopol 971P. Among the copolymers of maleic anhydride and alkenyl derivative, are the copolymers EMA (Monsanto), which are copolymers of maleic anhydride and ethylene. The dissolution of these polymers in water leads to an acid solution that will be neutralized, preferably to physiological pH, in order to give the adjuvant solution into which the immunogenic, immunological or vaccine composition itself will be incorporated.

Further suitable adjuvants include, but are not limited to, the RIM adjuvant system (Ribi Inc.), Block co-polymer (CytRx, Atlanta Ga.), SAF-M (Chiron, Emeryville Calif.), monophosphoryl lipid A, Avridine lipid-amine adjuvant, heat-labile enterotoxin from E. coli (recombinant or otherwise), cholera toxin, IMS 1314 or muramyl dipeptide, or naturally occurring or recombinant cytokines or analogs thereof or stimulants of endogenous cytokine release, among many others.

It is expected that an adjuvant can be added in an amount of about 100 μg to about 10 mg per dose, preferably in an amount of about 100 μg to about 10 mg per dose, more preferably in an amount of about 500 μg to about 5 mg per dose, even more preferably in an amount of about 750 μg to about 2.5 mg per dose, and most preferably in an amount of about 1 mg per dose. Alternatively, the adjuvant may be at a concentration of about 0.01 to 50%, preferably at a concentration of about 2% to 30%, more preferably at a concentration of about 5% to 25%, still more preferably at a concentration of about 7% to 22%, and most preferably at a concentration of 10% to 20% by volume of the final product.

In another specific aspect of the immunogenic composition according to the present invention the immunogenic composition is a vaccine. The term “vaccine” already has been described elsewhere herein. However, in case where the host displays a protective immunological response such that resistance to new infection will be enhanced and/or the clinical severity of the disease reduced, the immunogenic composition is described as a “vaccine.

Further, the present invention provides a cell comprising the nucleic acid molecule as described herein, the polynucleotide as described herein or the vector as described herein.

Further, the present invention provides a method of producing the nucleic acid molecule encoding the PEDV S protein as described herein and/or the PEDV S protein as described herein, comprising transfecting a cell with the vector as described herein.

Further, the present invention provides a method of preparing an immunogenic composition for the treatment and/or prophylaxis of PEDV infections in a subject comprising:

a.) infecting a cell with the vector as described herein;

b.) obtaining said vector; and

c.) addition of a pharmaceutically acceptable carrier.

The term “obtaining” comprises the harvest, isolation, purification and/or formulation (e.g. finishing, inactivation and/or blending) of the antigen.

The term “harvest” refers to collecting or recovering said vector from the transfected cell or cell line. Any conventional method known in the art can be used to recover said vector, e.g. any separation method. Well known methods in the art comprise centrifugation or filtration, such as using a semi-permeable membrane having a certain pore size.

The term “isolation” comprises an isolation step of said vector. Methods for the isolation of said vector from the infected cell or cell line are known to a person skilled in the art. Those methods comprise physical and/or chemical methods, including but are not limited to freeze thaw cycles, treatment with ultrasound and the alike.

Methods for the “purification” of said vector from the isolate are known to a person skilled in the art, for example by those methods described in Protein purification methods—a practical approach (E.L.V. Harris and S. Angel, eds., IRL Press at Oxford University Press). Those methods include, but are not limited to, separation by centrifugation and/or filtration, precipitation, size exclusion (gel filtration) chromatography, affinity chromatography, metal chelate chromatography, ion-exchange chromatography covalent chromatography, hydrophobic interaction chromatography, and the alike. The vector can be obtained in a purified pure form, or free or substantially free of other cellular materials or culture medium etc. After said isolation and/or purification the antigen exhibits a purity of at least 80%, preferably 80%-90%, more preferably 90%-97%, most preferred more than 97% up to an absolute pure form without any contamination.

According to a further aspect, “obtaining” as used herein may also include further finishing steps as part of the final formulation process, like the addition of buffer, inactivation, neutralization steps and the alike.

Preferably, the cell is from an eukaryotic cell line.

In a specific aspect of the method according to the present invention the cell is a Vero cell, ST cell or BHK-21, Ma104, MDBK, RK13, MDCK or PK15

All mentioned cell lines are well known to the person skilled in the art and are public available. Vero cells are exemplarily deposited at the American Tissue Culture Collection under accession number ATCC CCL-81. ST cells are exemplarily deposited at the American Tissue Culture Collection under accession number CRL-1746. BHK-21 cells are exemplarily deposited at the American Tissue Culture Collection under accession number ATCC CCL-10. MDCK cells are exemplarily deposited at the American Tissue Culture Collection under accession number ATCC CCL-34 or ATCC CRL-2285.

In another specific aspect of the immunogenic composition or the method according to the present invention said pharmaceutically acceptable carrier is selected from the group consisting of solvents, dispersion media, coatings, stabilizing agents, diluents, preservatives, antibacterial and antifungal agents, isotonic agents, adsorption delaying agents, adjuvants, immune stimulants, and combinations thereof.

Further, the present invention provides a method of immunizing a subject comprising administering to such subject an immunogenic composition as described herein.

Advantageously, the immunogenic composition of the present invention has been proven to be safe and efficacious.

The term “immunizing” relates to an active immunization by the administration of an immunogenic composition to a subject to be immunized, thereby causing an immunological response against the antigen included in such immunogenic composition.

Preferably, immunization results in lessening of the incidence of the particular PEDV infection in a herd or in the reduction in the severity of clinical signs caused by or associated with the particular PEDV infection.

Further, the immunization of a subject in need with the immunogenic compositions as provided herewith, results in preventing infection of a subject by PEDV infection. Even more preferably, immunization results in an effective, long-lasting, immunological-response against PEDV infection. It will be understood that the said period of time will last more than 1 month, preferably more than 2 months, preferably more than 3 months, more preferably more than 4 months, more preferably more than 5 months, more preferably more than 6 months. It is to be understood that immunization may not be effective in all subjects immunized. However, the term requires that a significant portion of subjects in a herd are effectively immunized.

Preferably, a herd of subjects is envisaged in this context which normally, i.e. without immunization, would develop clinical signs normally caused by or associated with a PEDV infection. Whether the subjects of a herd are effectively immunized can be determined without further ado by the person skilled in the art. Preferably, the immunization shall be effective if clinical signs in at least 33%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, still more preferably in at least 95% and most preferably in 100% of the subjects of a given herd are lessened in incidence or severity by at least 10%, more preferably by at least 20%, still more preferably by at least 30%, even more preferably by at least 40%, still more preferably by at least 50%, even more preferably by at least 60%, still more preferably by at least 70%, even more preferably by at least 80%, still more preferably by at least 90%, still more preferably by at least 95% and most preferably by 100% in comparison to subjects that are either not immunized or immunized with an immunogenic composition that was available prior to the present invention but subsequently infected by the particular PEDV.

Further, the present invention provides a method of treating and/or preventing clinical signs caused by PEDV infection in a subject of need, the method comprising administering to the subject a therapeutically effective amount of an immunogenic composition as described herein.

Advantageously, the immunogenic composition of the present invention has been proven to reduce the clinical signs caused by PEDV infection.

The term “treating and/or preventing” refers to the lessening of the incidence of the particular PEDV infection in a herd or the reduction in the severity of clinical signs caused by or associated with the particular PEDV infection. Thus, the term “treating and/or preventing” also refers to the reduction of the number of subjects in a herd that become infected with the particular PEDV (=lessening of the incidence of the particular PEDV infection) or to the reduction of the severity of clinical signs normally associated with or caused by a PEDV infection or the reduction of virus shedding after infection with the particular PEDV or preventing or reducing diarrhea after infection with the particular PEDV in a group of subjects which subjects have received an effective amount of the immunogenic composition as provided herein in comparison to a group of subjects which subjects have not received such immunogenic composition.

The “treating and/or preventing” generally involves the administration of an effective amount of the immunogenic composition of the present invention to a subject or herd of subjects in need of or that could benefit from such a treatment/prophylaxis. The term “treating” refers to the administration of the effective amount of the immunogenic composition once the subject or at least some subjects of the herd is/are already infected with such PEDV and wherein such subjects already show some clinical signs caused by or associated with such PEDV infection. The term “preventing” refers to the administration of a subject prior to any infection of such subject with PEDV or at least where such subject or none of the subjects in a group of subjects do not show any clinical signs caused by or associated with the infection by such PEDV. The terms “prophylaxis” and “preventing” are used interchangeable in this application.

The term “an effective amount” as used herein means, but is not limited to an amount of antigen, that elicits or is able to elicit an immune response in a subject. Such effective amount is able to lessen the incidence of the particular PEDV infection in a herd or to reduce the severity of clinical signs of the particular PEDV infection.

Preferably, clinical signs are lessened in incidence or severity by at least 10%, more preferably by at least 20%, still more preferably by at least 30%, even more preferably by at least 40%, still more preferably by at least 50%, even more preferably by at least 60%, still more preferably by at least 70%, even more preferably by at least 80%, still more preferably by at least 90%, still more preferably by at least 95% and most preferably by 100% in comparison to subjects that are either not treated or treated with an immunogenic composition that was available prior to the present invention but subsequently infected by the particular PEDV.

The term “clinical signs” as used herein refers to signs of infection of a subject from PEDV. Examples for such clinical signs include but are not limited to virus load, diarrhea, shedding, increased body temperature, mortality, gross pathological lesions in the intestine, depression, weight loss, reduced growth rates and reduced appetite. However, the clinical signs also include but are not limited to clinical signs that are directly observable from a live animal. Examples for clinical signs that are directly observable from a live animal include weight loss, reduced growth rates, reduced appetite, dehydration, watery diarrhea, vomiting, lameness, lethargy, wasting and unthriftiness and the like.

Preferably, the clinical signs lessened in incidence or severity in a treated subject compared to subjects that are either not treated or treated with an immunogenic composition that was available prior to the present invention but subsequently infected by the particular PEDV refer to a reduction in weight loss, a lower virus load, a reduction of diarrhea, a reduced shedding, a reduced rectal temperature, mortality, reduced gross pathological lesions in the intestine, or combinations thereof.

The term “in need” or “of need”, as used herein means that the administration/treatment is associated with the boosting or improvement in health or clinical signs or any other positive medicinal effect on health of the subjects which receive the immunogenic composition in accordance with the present invention.

Further, the present invention provides a method of reducing the diarrhea in a subject in comparison to a subject of a non-immunized control group of the same species, the method comprising administering to the subject a therapeutically effective amount of an immunogenic composition as described herein.

Further, the present invention provides a method of reducing the mortality in a subject in comparison to a subject of a non-immunized control group of the same species, the method comprising administering to the subject a therapeutically effective amount of an immunogenic composition as described herein.

The term “reducing the mortality” means that the mortality is reduced by at least 10%, more preferably by at least 20%, still more preferably by at least 30%, even more preferably by at least 40%, still more preferably by at least 50%, even more preferably by at least 60%, still more preferably by at least 70%, even more preferably by at least 80%, even more preferably by at least 90%, still more preferably by at least 95% most preferably by 100% in comparison to subjects that are not treated (not immunized) but subsequently infected by the particular PEDV.

Thus, it has to be understood that a subject can be vaccinated with the immunogenic composition according to the present invention for reducing or preventing clinical signs such as diarrhea or mortality in said subject. Preferably, said subject is a piglet, pig or sow.

Further, the present invention provides a method for inducing the production of antibodies specific for PEDV in a subject, wherein said method comprises administering the immunogenic composition as described herein to said subject. Preferably, said subject is a piglet, pig or sow.

Further, the present invention provides a method for inducing the production of antibodies specific for PEDV in a sow, wherein said method comprises administering the immunogenic composition as described herein to said sow.

The term “antibodies specific for PEDV” refers to detectable anti-PEDV antibodies. Further, the anti-PEDV antibodies in the sow have been developed in response to the vaccination with the PEDV vaccine according to the present invention. The term “antibodies specific for PEDV” or “antibodies specific for PEDV in a sow” shall further mean, but is not limited to, a sow that has a detectable anti-PEDV antibody titer, preferably of at least 1:10, more preferably of more than 1:20, even more preferably of more than 1:40, even more preferably of more than 1:80, even more preferably of 1:160, even more preferably of more than 1:320, and most preferably of more than 1:640. Preferably, that anti-PEDV antibody titer is detectable and quantifiable in a specific anti-PEDV immune assay.

Advantageously, the immunogenic composition of the present invention has been shown to induce the production of antibodies specific for PEDV in a sow.

It is well known by the person skilled in the art how to detect the production of antibodies specific for PEDV such as by an ELISA Assay (ELISAs are commercially available).

Further, the present invention provides a method of reducing the diarrhea in a piglet in comparison to a piglet of a non-immunized control group, the method comprising administering to the sow of the piglet a therapeutically effective amount of an immunogenic composition as described herein, wherein the piglet is to be suckled by said sow. The term “sow of the piglet”, as used herein, is in particular understood to be equivalent to “mother sow of the piglet” or “nurse sow of the piglet”, respectively.

Further, the present invention provides a method of reducing the mortality in a piglet in comparison to a piglet of a non-immunized control group, the method comprising administering to the sow of the piglet a therapeutically effective amount of an immunogenic composition as described herein, wherein the piglet is to be suckled by said sow.

Further, the present invention provides a method of reducing or preventing the clinical signs or disease caused by an infection with a PEDV in a piglet, wherein the piglet is to be suckled by a sow to which the immunogenic composition as described herein has been administered.

Preferably, the clinical sign that is reduced is mortality. Thus, the present invention also provides a method of reducing the mortality caused by an infection with a PEDV in a piglet, wherein the piglet is to be suckled by a sow to which the immunogenic composition as described herein has been administered.

Further, the present invention provides a method of reducing or preventing the clinical signs or disease caused by an infection with a PEDV in a piglet, wherein said method comprises

-   -   administering the immunogenic composition as described herein to         a sow, and     -   allowing said piglet to be suckled by said sow or, respectively,         allowing said piglet to suckle said sow.

Advantageously, the immunogenic composition of the present invention has been shown to reduce clinical signs in pigs when administered to sows during pregnancy.

In case piglets are vaccinated with the immunogenic composition of the present invention it has to be understood that time is needed for actual antibody production in said piglet. Therefore, in another aspect of the method present invention the sow being pregnant is vaccinated with the immunogenic composition of the present invention. Said vaccination results in the production of antibodies specific for PEDV in said sow. The maternally derived antibodies from said sow are then passively transferred to the newborn piglets via colostrum and/or milk.

In another specific aspect of the method according to the present invention said sow to which the immunogenic composition is administered is a sow being pregnant, in particular with said piglet. However, it is to be understood that the piglet can be suckled by any sow giving colostrum or milk, wherein said sow is in particular a sow to which said immunogenic has been administered.

In another specific aspect the method according to the present invention comprising the steps of

-   -   administering the immunogenic composition as described herein to         a sow being pregnant with said piglet,     -   allowing said sow to give birth to said piglet, and     -   allowing said piglet to be suckled by said sow.

In another specific aspect of the method according to the present invention said method results in an improvement in a clinical sign or efficacy parameter selected from the group consisting of: a reduction in weight loss, a lower virus load, a reduction of diarrhea, a reduced shedding, a reduced rectal temperature, reduced mortality, reduced gross pathological lesions in the intestine, or combinations thereof, in comparison to a subject of a non-immunized control group of the same species.

In another specific aspect of the method according to the present invention said subject is a piglet, pig or sow.

Preferably, the immunogenic composition is administered to the subject within the first two months of age, more preferably, within the first month of age.

In another specific aspect of the method according to the present invention the immunogenic composition is administered to the subject within the first month of age.

Thus, it has to be understood that the immunogenic composition can be administered to the subject exemplary within the first three weeks of age or within the first two weeks of age.

In another specific aspect of the method according to the present invention said immunogenic composition is administered to sows during pregnancy and lactation.

Advantageously, the immunogenic composition of the present invention has been proven to be safe when administered to sows during pregnancy.

Thus, there is provided a method of vaccinating pigs against PEDV by administering the PEDV vaccine according to the present invention to a pregnant sow at least two times before farrowing, preferably three times before farrowing, more preferably two times before farrowing (“repeated doses”). Preferably, the pregnant sow is vaccinated with the PEDV vaccine according to the present invention twice with a single dose of said vaccine before farrowing. However, when the vaccine is administered to the sow two times, the first administration should occur between 12 and 4 weeks before farrowing, more preferably between 9 and 5 weeks before farrowing. The second administration should occur between 8 and 1 week before farrowing, more preferably between 6 and 1 week before farrowing.

In another specific aspect of the method according to the present invention the immunogenic composition is administered at two or more doses.

Advantageously, the immunogenic composition of the present invention has been shown to induce the production of antibodies specific for PEDV after two doses.

In another specific aspect of the method according to the present invention said immunogenic composition is administered to sows two times, the first administration between 9 and 5 weeks before farrowing and the second administration between 6 and 1 week before farrowing.

The immunogenic composition is, preferably, administered topically or systemically. Suitable routes of administration conventionally used are oral or parenteral administration, such as intranasal, intravenous, intramuscular, intraperitoneal, subcutaneous, as well as inhalation. However, depending on the nature and mode of action of a compound, the immunogenic composition may be administered by other routes as well. However, most preferred the immunogenic composition is administered intranasal or oral.

In another specific aspect of the method according to the present invention said immunogenic composition is administered intranasal, mucosal, oral, intradermal or intramuscular.

Advantageously, the immunogenic composition of the present invention has been proven to be effective when administered intranasal.

In another specific aspect of the method according to the present invention said immunogenic composition is administered intranasal or oral.

Preferably, the immunogenic composition comprises between 1×10² to 1×10⁹ TCID₅₀/ml, more preferably between 1×10³ to 1×10⁷ TCID₅₀/ml and most preferably between 1×10⁴ to 1×10⁶ TCID₅₀/ml.

In another specific aspect of the method according to the present invention the immunogenic composition comprises between 1×10³ to 1×10⁷ TCID₅₀/ml.

The term “TCID₅₀/ml” refers to the measure of infectious virus titer. Specifically the tissue culture infectious dose fifty per milliliter (TCID_(50/)ml) gives the dilution of a virus preparation at which 50% of a number of cell cultures inoculated in parallel with that dilution are infected.

In another specific aspect of the method according to the present invention the method results in a reduction of the shedding from day 2 after challenge or infection.

In another specific aspect of the method according to the present invention the method results in a reduction of the shedding from day 3 after challenge or infection.

In another specific aspect of the method according to the present invention the method results in a reduction of the shedding from day 4 after challenge or infection.

In another specific aspect of the method according to the present invention the method results in a reduction of the shedding from day 5 after challenge or infection.

In another specific aspect of the method according to the present invention the method results in a reduction of the shedding from day 7 after challenge or infection.

In another specific aspect of the method according to the present invention the method results in a reduction of the shedding from day 10 after challenge or infection.

In another specific aspect of the method according to the present invention the method results in a reduction of the shedding from day 5, 7 or 10 after challenge or infection.

Advantageously, the immunogenic composition of the present invention has been proven to reduce the shedding after infection or challenge.

The term “reduction of the shedding” means that the shedding is reduced by at least 10%, more preferably by at least 20%, still more preferably by at least 30%, even more preferably by at least 40%, still more preferably by at least 50%, even more preferably by at least 60%, still more preferably by at least 70%, even more preferably by at least 80%, even more preferably by at least 90%, still more preferably by at least 95% most preferably by 100% in comparison to subjects that are not treated (not immunized) but subsequently infected by the particular PEDV. It is in the general knowledge of a person skilled in the art how to measure the viral shedding.

The term “shedding” refers to secretions of PEDV in fecal discharges or feces. Thus, shedding may be determined by examining the virus titer in fecal discharges, feces or rectal swaps. The term “shedding” further encompasses the transfer of virus to susceptible animals (i.e. sentinels). It is in the general knowledge of a person skilled in the art how to measure the viral shedding such as by PCR, qPCR or ELISA.

In another specific aspect of the method according to the present invention the method increases the protection against a homologous challenge.

Advantageously, the immunogenic composition of the present invention has been proven to be protective after challenge.

The invention provides the use of the nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein, the PEDV (S) protein or the or immunogenic composition as described herein for the manufacture of a medicament.

The invention also provides the use of the nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein, the PEDV (S) protein or the immunogenic composition as described herein for treating and/or preventing clinical signs caused by PEDV infection in a subject or for reducing diarrhea in a subject.

Sequence Overview

The following sequences are detailed and disclosed hereby in the present invention:

-   SEQ ID NO:1: RSXIEDXX, -   SEQ ID NO:2: wild type G2a PEDV S amino acid sequence US, -   SEQ ID NO:3: wild type G2b PEDV S amino acid sequence EU, -   SEQ ID NO:4: RSXIEDLLF, -   SEQ ID NO:5: RSXIEDAAF, -   SEQ ID NO:6: XXXFXKXXXX, -   SEQ ID NO:7: YXXFXKXH, -   SEQ ID NO:8: AXXFXKXR, -   SEQ ID NO:9: PEDV S European strain genotype 2b (G2b) sequence with     mutation 897A, -   SEQ ID NO:10: PEDV S European strain genotype 2b (G2b) sequence with     mutation at amino acid position 898 to A, -   SEQ ID NO:11: PEDV S European strain genotype 2b (G2b) sequence with     mutation 897A and 898A, -   SEQ ID NO:12: PEDV S European strain genotype 2b (G2b) sequence with     mutation 897A and 1374A and 1381R, -   SEQ ID NO:13: PEDV S European strain genotype 2b (G2b) sequence with     mutation 898A and 1374A and 1381R, -   SEQ ID NO:14: PEDV S European strain genotype 2b (G2b) sequence with     mutation 897A, 898A and 1374A and 1381R, -   SEQ ID NO:15: PEDV S US strain genotype 2a (G2a) sequence with     mutation 900A, -   SEQ ID NO:16: PEDV S US strain genotype 2a (G2a) sequence with     mutation at amino acid position 901 to A, -   SEQ ID NO:17: PEDV S US strain genotype 2a (G2a) sequence with     mutation 900A and 901A, -   SEQ ID NO:18: PEDV S US strain genotype 2a (G2a) sequence with     mutation 900A and 1377A and 1384R, -   SEQ ID NO:19: PEDV S US strain genotype 2a (G2a)sequence with     mutation 901A and 1377A and 1384R, -   SEQ ID NO:20: PEDV S US strain genotype 2a (G2a) sequence with     mutation 900A, 901A and 1377A and 1384R, -   SEQ ID NO:21: RSXIEDLX, -   SEQ ID NO:22: RSXIEDXL, -   SEQ ID NO:23: RSXIEDLA, -   SEQ ID NO:24: RSXIEDAL, -   SEQ ID NO:25: RSXIEDAA, -   SEQ ID NO:26: XXXFXKXHXX, -   SEQ ID NO:27: YXXFXKXXXX, -   SEQ ID NO:28: AXXFXKXHXX, -   SEQ ID NO:29: YXXFXKXRXX, -   SEQ ID NO:30: AXXFXKXRXX, -   SEQ ID NO:31: RSXIEDLG, -   SEQ ID NO:32: RSXIEDGL, -   SEQ ID NO:33: RSXIEDGG, -   SEQ ID NO:34: RSXIEDGA, -   SEQ ID NO:35: RSXIEDAG, -   SEQ ID NO:36 comprises a cloning cassette of PEDV spike     protein—including duplication of the UTR regions for the inserted     gene, -   SEQ ID NO:37 (RNA) corresponds to a sequence encoding the S protein     of SEQ ID NO:14, -   SEQ ID NO:38 (RNA) corresponds to a sequence comprising SEQ ID     NO:37, -   SEQ ID NO:39: wild type G2a PEDV S amino acid sequence CN, -   SEQ ID NO:40: PEDV S CN strain genotype 2a (G2a) sequence with     mutation 900A, 901A and 1377A and 1384R, -   SEQ ID NOs:41-44: probe, primer, and ultramer sequences (Table 2).

As in the sequence listing amino acid sequences are presented in the three-letter code format using the symbol “Xaa” as equivalent for the variable “X”, it is in particular understood that the wording “X at residue” provided in the sequence listing is equivalent to “Xaa at residue”.

CLAUSES

The following Clauses are described herein:

The invention provides the following clauses:

1. A nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein comprising the amino acid sequence

(SEQ ID NO: 1) RSX₁IEDX ₂ X ₃,

wherein

(I) X₂ is an amino acid residue other than a leucine residue and X₃ is a leucine residue, or

(II) X₂ is a leucine residue and X₃ is an amino acid residue other than a leucine residue, or

(III) X₂ is an amino acid residue other than a leucine residue and X₃ is an amino acid residue other than a leucine residue.

2. The nucleic acid molecule of clause 1 comprising the amino acid sequence

RSX₁IEDX₂X₃ (SEQ ID NO:1), wherein

-   -   R is the arginine residue at amino acid position 894 if the PEDV         S protein is a genotype 2a (G2a) PEDV S protein and wherein the         numbering of the amino acid position refers to the amino acid         sequence of wild type G2a PEDV S protein, or     -   R is the arginine residue at amino acid position 891 if the PEDV         protein is a genotype 2b (G2b) PEDV S protein and wherein the         numbering of the amino acid position refers to the amino acid         sequence of wild type G2b PEDV S protein.

3. The nucleic acid molecule of clause 2, wherein

-   -   the amino acid sequence of wild type G2a PEDV S protein is the         amino acid sequence of wild type G2a PEDV S protein of SEQ ID         NO:2 or SEQ ID NO:39, and/or     -   the amino acid sequence of wild type G2b PEDV S protein is the         amino acid sequence of wild type G2b PEDV S protein of SEQ ID         NO:3.

4. A nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein comprising the amino acid sequence

(SEQ ID NO: 1) RSX₁IEDX ₂ X ₃,

wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein, X₁ can be any amino acid residue and wherein

(I) X₂ is an amino acid residue other than a leucine residue and X₃ is a leucine residue, or

(II) X₂ is a leucine residue and X₃ is an amino acid residue other than a leucine residue, or

(III) X₂ is an amino acid residue other than a leucine residue and X₃ is an amino acid residue other than a leucine residue.

5. A nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein selected from the group consisting of the following (a) and (b):

(a) a genotype 2a (G2a) PEDV S protein having at least one mutation, wherein

-   -   the leucine residue at amino acid position 900 is substituted by         an amino acid residue other than a leucine residue, and/or     -   the leucine residue at amino acid position 901 is substituted by         an amino acid residue other than a leucine residue,

wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2a PEDV S protein of SEQ ID NO:2 or SEQ ID NO:39,

(b) a genotype 2b (G2b) PEDV S having at least one mutation, wherein

-   -   the leucine residue at amino acid position 897 is substituted by         an amino acid residue other than a leucine residue, and/or     -   the leucine residue at amino acid position 898 is substituted by         an amino acid residue other than a leucine residue,

wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2b PEDV S protein of SEQ ID NO:3.

6. The nucleic acid molecule of any one of clauses 1 to 5, wherein said amino acid residue other than a leucine residue is selected from the group consisting of alanine residue, glycine residue, isoleucine residue, methionine residue and valine residue.

The nucleic acid molecule of any one of clauses 1 to 6, wherein said amino acid residue other than a leucine residue is an alanine residue.

8. The nucleic acid molecule of any one of clauses 5 to 7, wherein the numbering of the amino acid positions refer to the amino acid sequence RSXIEDLLF (SEQ ID NO:4) of wild type G PEDV S protein, wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein and LL are the amino acid positions 900 and 901 within the genotype 2a (G2a) PEDV S protein or LL are the amino acid positions 897 and 898 within the genotype 2b (G2b) PEDV S protein.

9. The nucleic acid molecule of any one of clauses 5 to 8, wherein the numbering of the amino acid positions refer to the amino acid sequence RSXIEDLLF (SEQ ID NO:4) of wild type G PEDV S protein, wherein R is the arginine residue at amino acid position 894 and LL are the amino acid positions 900 and 901 within the genotype 2a (G2a) PEDV S protein, or R is the arginine residue at amino acid position 891 and LL are the amino acid positions 897 and 898 within the genotype 2b (G2b) PEDV S protein.

10. The nucleic acid molecule of any one of clauses 1 to 9, wherein said PEDV S protein comprises the amino acid sequence RSXIEDAAF (SEQ ID NO:5), wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein and AA are the amino acid positions 900 and 901 within the genotype 2a (G2a) PEDV S protein or AA are the amino acid positions 897 and 898 within the genotype 2b (G2b) PEDV S protein.

11. The nucleic acid molecule of any one of clauses 1 to 10, wherein said PEDV S protein comprises the amino acid sequence RSXIEDAAF (SEQ ID NO:5), wherein R is the arginine residue at amino acid position 894 and AA are the amino acid positions 900 and 901 within the genotype 2a (G2a) PEDV S protein, or R is the arginine residue at amino acid position 891 and AA are the amino acid positions 897 and 898 within the genotype 2b (G2b) PEDV S protein.

12. The nucleic acid molecule of any one of clauses 1 to 11, wherein said PEDV S protein further comprises the amino acid sequence

(SEQ ID NO: 6) X ₁X₂X₃FX₄KX₅ X ₆X₇X₈,

wherein X₈ is the C-terminal amino acid residue of said PEDV S protein or the amino acid residue at the −2 position relative to the C-terminal amino acid position of said PEDV S protein,

X₂ to X₅, X₇ and X₈ can be any amino acid residue, and wherein

(i) X₁ is an amino acid residue other than a tyrosine residue and X₆ is a histidine residue, or

(ii) X₁ is a tyrosine residue and X₆ is an amino acid residue other than a histidine residue, or

(iii) X₁ is an amino acid residue other than a tyrosine residue and X₆ is an amino acid residue other than a histidine residue.

13. The nucleic acid molecule of any one of clauses 5 to 13, wherein

(a) in said G2a PEDV S protein further

-   -   the tyrosine residue at amino acid position 1377 is substituted         by an amino acid residue other than a tyrosine residue, and/or     -   the histidine residue at amino acid position 1384 is substituted         by an amino acid residue other than a histidine residue,

or

(b) in said G2b PEDV S protein further

-   -   the tyrosine residue at amino acid position 1374 is substituted         by an amino acid residue other than a tyrosine residue, and/or     -   the histidine residue at amino acid position 1381 is substituted         by an amino acid residue other than a histidine residue.

14. The nucleic acid molecule of clause 12 to 13, wherein

-   -   said amino acid residue other than a tyrosine residue is         selected from the group consisting of alanine residue, glycine         residue, leucine residue, isoleucine residue, methionine residue         and valine residue, and/or     -   said amino acid residue other than a histidine residue is an         arginine residue. 15. The nucleic acid molecule of any one of         clauses 12 to 14, wherein     -   said amino acid residue other than a tyrosine residue is an         alanine residue, and/or     -   said amino acid residue other than a histidine residue is an         arginine residue.

16. The nucleic acid molecule of any one of clauses 13 to 15, wherein the numbering of the amino acid positions refers to the amino acid sequence YXXFXKXH (SEQ ID NO:7) of wild type G PEDV S protein, wherein Y and H are the amino acid positions 1377 and 1384 within the genotype 2a (G2a) PEDV S protein or Y and H are the amino acid positions 1374 and 1381 within the genotype 2b (G2b) PEDV S protein.

17. The nucleic acid molecule of any one of clauses 12 to 16, wherein the nucleic acid molecule comprises a sequence encoding the amino acid sequence AXXFXKXR (SEQ ID NO:8), wherein A and R are the amino acid positions 1377 and 1384 within the genotype 2a (G2a) PEDV S protein or A and R are the amino acid positions 1374 and 1381 within the genotype 2b (G2b) PEDV S protein.

18. The nucleic acid molecule of any one of clauses 1 to 17, wherein said PEDV S protein:

i) (a) comprises or consists of an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 15, 16, 17, 18, 19, 20, 40, or

(b) comprises or consists of an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 9, 10, 11, 12, 13, 14; and/or

ii) (a) is encoded by a nucleotide sequence encoding an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence any one of SEQ ID NOS: 15, 16, 17, 18, 19, 20, 40, or

(b) is encoded by a nucleotide sequence encoding an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 9, 10, 11, 12, 13, 14.

19. The nucleic acid molecule of any one of clauses 1 to 18, wherein said PEDV S protein

(a) comprises the amino acid sequence of any one of SEQ ID NOS: 15, 16, 17, 18, 19, 20, 40, or

(b) comprises the amino acid sequence of any one of SEQ ID NOS: 9, 10, 11, 12, 13, 14.

20. A PEDV (S) protein encoded by the nucleic acid molecule of any one of clauses 1 to 19.

21. The nucleic acid molecule of any one of clauses 1 to 19 or the PEDV S protein of clause 20, wherein said nucleic acid molecule encoding the PEDV S protein or the PEDV S protein is recombinant.

22. A polynucleotide comprising the nucleic acid molecule of any one of clauses 1 to 19.

23. A vector comprising the nucleic acid molecule of any one of clauses 1 to 19 or the polynucleotide of clause 22.

24. The vector of clause 23, wherein the vector is a CDV, EHV, ORF virus, PRV, CAV, PCMV or BoHV-4.

25. The vector of clause 23, wherein the vector is a CDV or EHV.

26. An immunogenic composition comprising the nucleic acid molecule encoding the PEDV S protein of any one of clauses 1 to 19 and/or the PEDV S protein of clause 20 and/or the vector of any one of clauses 23 to 25.

27. The immunogenic composition of clause 26, wherein the immunogenic composition further comprises a pharmaceutically acceptable carrier.

28. The immunogenic composition of clause 26 or 27, wherein the immunogenic composition is a vaccine.

29. A cell comprising the nucleic acid molecule of any one of clauses 1 to 19, the polynucleotide of clause 22 or the vector of any one of clauses 23 to 25.

30. A method of producing the nucleic acid molecule encoding the PEDV S protein of any one of clauses 1 to 19 and/or the PEDV S protein of clause 20, comprising transfecting a cell with the vector of any one of clauses 23 to 25.

31. A method of preparing an immunogenic composition for the treatment and/or prophylaxis of PEDV infections in a subject comprising:

a.) infecting a cell with the vector of any one of clauses 23 to 25;

b.) obtaining said vector; and

c.) addition of a pharmaceutically acceptable carrier.

32. The cell of clause 29 or the method of clause 30 or 31, wherein the cell is a Vero cell, ST cell, BHK-21 cell, Ma104 cell, MDBK cell, RK13 cell, MDCK cell or PK15 cell.

33. The immunogenic composition of clause 27 or the method of clause 31, wherein said pharmaceutically acceptable carrier is selected from the group consisting of solvents, dispersion media, coatings, stabilizing agents, diluents, preservatives, antibacterial and antifungal agents, isotonic agents, adsorption delaying agents, adjuvants, immune stimulants, and combinations thereof.

34. A method of immunizing a subject comprising administering to the subject an immunogenic composition of any one of clauses 26 to 28.

35. The immunogenic composition of any one of clauses 26 to 28 for use in a method of immunizing a subject, the method comprising administering to the subject a therapeutically effective amount of said immunogenic composition.

36. A method of treating and/or preventing clinical signs caused by PEDV infection in a subject of need, the method comprising administering to the subject a therapeutically effective amount of an immunogenic composition according to any one of clauses 26 to 28.

37. The immunogenic composition of any one of clauses 26 to 28 for use in a method of treating and/or preventing clinical signs caused by PEDV infection in a subject of need, the method comprising administering to the subject a therapeutically effective amount of said immunogenic composition.

38. A method of reducing the mortality in a subject in comparison to a subject of a non-immunized control group of the same species, the method comprising administering to the subject a therapeutically effective amount of an immunogenic composition according to any one of clauses 26 to 28.

39. The immunogenic composition of any one of clauses 26 to 28 for use in a method of reducing the mortality in a subject in comparison to a subject of a non-immunized control group of the same species, the method comprising administering to the subject a therapeutically effective amount of said immunogenic composition.

40. A method for inducing the production of antibodies specific for PEDV in a sow, wherein said method comprising administering the immunogenic composition of any one of clauses 26 to 28 to said sow.

41. The immunogenic composition of any one of clauses 26 to 28 for use in a method for inducing the production of antibodies specific for PEDV in a sow, the method comprising administering to said sow a therapeutically effective amount of said immunogenic composition.

42. A method of reducing the mortality in a piglet in comparison to a piglet of a non-immunized control group, the method comprising administering to the sow of the piglet a therapeutically effective amount of an immunogenic composition according to any one of clauses 26 to 28, wherein the piglet is to be suckled by said sow.

43. The immunogenic composition of any one of clauses 26 to 28 for use in a method of reducing the mortality in a piglet in comparison to a piglet of a non-immunized control group, the method comprising administering to the sow of the piglet a therapeutically effective amount of said immunogenic composition, wherein the piglet is to be suckled by said sow.

44. A method of reducing or preventing the clinical signs or disease caused by an infection with a PEDV in a piglet, wherein the piglet is to be suckled by a sow to which the immunogenic composition of any one of clauses 26 to 28 has been administered.

45. The immunogenic composition of any one of clauses 26 to 28 for use in a method of reducing or preventing the clinical signs or disease caused by an infection with a PEDV in a piglet, wherein the piglet is to be suckled by a sow to which the said immunogenic composition has been administered.

46. A method of reducing or preventing the clinical signs or disease caused by an infection with a PEDV in a piglet, wherein said method comprises

-   -   administering the immunogenic composition of any one of clauses         26 to 28 to a sow, and     -   allowing said piglet to be suckled by said sow.

47. The immunogenic composition of any one of clauses 26 to 28 for use in a method of reducing or preventing the clinical signs or disease caused by an infection with a PEDV in a piglet, wherein said method comprises

-   -   administering said immunogenic composition to a sow, and     -   allowing said piglet to be suckled by said sow.

48. The method of any one of clauses 34 to 47, wherein said sow to which the immunogenic composition is administered is a sow being pregnant, in particular with said piglet.

49. The method of any one of clauses 34, and 46 to 48, comprising the steps of

-   -   administering the immunogenic composition of any one of clauses         26 to 28 to a sow being pregnant with said piglet,     -   allowing said sow to give birth to said piglet, and     -   allowing said piglet to be suckled by said sow.

50. The method of any one of clauses 36, 37, 40, 44, 45, 46, 47, 48 or 49, wherein said method results in an improvement in a clinical sign or efficacy parameter selected from the group consisting of: a reduction in weight loss, a lower virus load, a reduction of diarrhea, a reduced shedding, a reduced rectal temperature, reduced mortality, reduced gross pathological lesions in the intestine, or combinations thereof, in comparison to a subject of a non-immunized control group of the same species.

51. The method of any one of clauses 34 to 39, wherein said subject is a piglet, pig or sow.

52. The method of any one of clauses 34 to 39 or 51, wherein the immunogenic composition is administered to the subject within the first month of age.

53. The method of any one of clauses 34 to 52, wherein said immunogenic composition is administered to sows during pregnancy and lactation.

54. The method of any one of clauses 34 to 53, wherein the immunogenic composition is administered at two or more doses.

55. The method of any one of clauses 34 to 44, wherein said immunogenic composition is administered to sows two times, the first administration between 9 and 5 weeks before farrowing and the second administration between 6 and 1 week before farrowing.

56. The method of any one of clauses 34 to 55, wherein said immunogenic composition is administered intranasally, mucosally, orally, intradermally or intramuscularly.

57. The method of any one of clauses 34 to 56, wherein said immunogenic composition is administered intranasally or orally.

58. The method of any one of clauses 34 to 57, wherein the immunogenic composition comprises between 1×10³ to 1×10⁷ TCID₅₀/ml, in particular of a vector according to any one of clauses 23 to 25.

59. The method of any one of clauses of 34 to 58, wherein the method results in a reduction of the shedding from day 5, 7 or 10 after challenge or infection.

60. The method of any one of clauses 34 to 59, wherein the method increases the protection against a homologous challenge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following examples set forth preferred materials and procedures in accordance with the present invention. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods, devices, and materials are now described. It is to be understood, however, that these examples are provided by way of illustration only, and nothing therein should be deemed a limitation upon the overall scope of the invention.

Example 1 Preparation of the Spike Modifications

-   A) PEDV-S Expression by Recombinant CDV Vectors

In an in vitro experiment, a full plasmid (pBR322) encoding fully CDV genome derived from Lederle vaccine strain (Lederle; ATCC VR-128) was digested using SacII endonuclease followed by cloning PEDV spike (S) protein encoding cassette between the P gene and the M gene (resulting in a sequence comprising SEQ ID NO:36). Upon cloning and rescue of recombinant CDV-PEDV-S, it was possible to show expression of Porcine Epidemic Diarrhea Virus spike protein of a 2b genotype in CDV associated fluorescent focuses. Respective results are also achieved for a corresponding CDV vector (i.e. only differing in the sequence encoding the Porcine Epidemic Diarrhea Virus spike protein of a 2a genotype SEQ ID NO:20). Results obtained for both vectors by immunofluorescence indicate strong expression of spike protein of PEDV in all CDV infected syncytia (data not shown).

-   B) Preparation of EHV Expressing PEDV Spike

For generating EHV1 recombinants expressing spike proteins PEDV-52b-wt and PEDV-S2b-mut synthetic sequence SEQ ID NO:3 and SEQ ID NO:14 was used. Its sequence was synthesized and subcloned in the transfer vector pUC19-ORF1/3-PEDV-52b-wt and pUC19-ORF1/3-PEDV-S2b-mut respectively.

By en-passant mutagenesis using the RED recombination system (Tischer et al. 2006) the expression cassette of PEDV-S2b-wt or PEDV-S2b-mut was inserted in orf1/3 region of pRacH-SE to produce final BAC DNA pRacH-SE- PEDV-S2b-wt and pRacH-SE- PEDV-S2b-mut.

RK13 cells were transfected with generated BAC DNA, recombinant viruses rEHV-1 were rescued and plaque-purified. Correct insertion of the expression cassette was verified by sequencing of a high-fidelity PCR product of the insertion region. Expression of the transgene in infected cells was analyzed and confirmed by indirect immunofluorescence assay (IFA) (data not shown). Furthermore, the virus was passaged for 20 cell passages in RK-13 cells to confirm in vitro stability of the constructs.

Example 2 Localization of Spike in Plasma Membrane

EHV-1 recombinant vector encoding wild type (naturally occurring) PEDV-S protein of 2b genotype (EHV1-PEDV-S2b-wt) was compared with EHV-1 recombinant vector encoding mutated spike protein (on amino acid positions 897/ 898 / 1374 / 1381 (SEQ ID NO:14)—designated as EHV1-PEDV-S2b-mut).

Briefly, RK13 cells were plated in the 6-wells cell culture plates at the density of 2×10⁵ of the cells to one well of the six well plate. On the next day (24 h post seeding), the cells were infected with either EHV1-PEDV-S2b-wt or EHV1-PEDV-S2b-mut at MOI of 0.01. Two days post infection (48 hours) the cells were fixed using 3% paraformaldehyde solution for one hour. Fixed cell monolayers, were than permabilized using 0.1% Tween20 and then stained for 1 hour using mouse anti-PEDV monoclonal antibodies clone 7D7_G1 (Abpro-Labs 2.4.16) using 1:200 dilution in PBS. After one hour the cells were washed twice with room temperature PBS (1000 μl per well). Add 750 μ1 of 1:500 dilution of commercial secondary antibody (Goat anti Mouse-FITC (Life Technology cat:A11029 lot:1705900) per well and incubated for 60 minutes in the dark (protected from light). After the incubation, secondary antibody solution was aspirated by vacuum, followed by twice Wash with room temperature PBS (1000 μl per well). The results were obtained using Olimpus inverted fluorescent microscope (mod.IX81), using FITC filter to detect specific fluorescence of PEDV spike protein in the cells (FIG. 1). The spike protein expressed from EHV1-PEDV-S2b-wt recombinant vector is primarily localized in the cytoplasm, while spike protein expressed from EHV1-PEDV-S2b-mut is localized primarily within the cellular membrane.

Example 3 Growth Kinetics in Vero Cells

Introduction: Efficient growth of recombinant viral vector is one of the essential features regarding the efficient production of the vaccine. Canine distemper virus (CDV) vaccines are produced on Vero cells (ATCC® CCL-81™) and very often using a roller bottle production system. We compared the growth kinetics of two CDV recombinants, that were: _(i) a CDV backbone derived from Lederle vaccine strain (c.f. Example 1) with an insert of the sequence of SEQ ID NO:39 (encoding the PEDV Spike protein of SEQ ID NO:20) between the P gene and the M gene, named “CDV-PEDV-spike-MUT” or “CDV-PEDV-spike mut” herein, and (ii) a respective vector encoding the corresponding wild type protein (the PEDV Spike protein of SEQ ID NO:2), named “CDV-PEDV-spike-WT” or “CDV-PEDV-spike wt” herein.

Experimental setup: Roller bottles (490 cm³) were seeded with 2×10⁷ of Vero cells. On the next day, CDV-PEDV-spike-MUT or CDV-PEDV-spike-WT virus stocks were used to infect the Vero cells in roller bottles at the MOI of 0.01. In the following 7 days, 1 ml aliquots we sampled from each roller bottle in triplicates. All samples were stored in −80° C. freezers until analysis. On the day of analysis, the samples were thawed on ice and virus titration was performed following the protocol:

CDV Titration Protocol Material

Cells: VeroDogSLAM BI seeded 24 hrs before in 96 well plates, 6×10³ cells/well

Media: MEM (SAFC, SLBX3503)

48 well plate for dilution

Procedure

Use 48 well plate for dilution

Fill wells with 1080μ1 of MEM

Pipet 120 μl of each sample in the first row

Mix program, make a 10-fold dilution from 10{circumflex over ( )}A-1 to 10{circumflex over ( )}-8 of each sample.

For each dilution one 96well plate of cells is used.

Transfer the dilution on the pre-seeded cells (100 μl/well)

Make 8× replicates of for each sample

Incubation for 3 days at 37° C. cell incubators

Readout using microscopy by detecting the typical CDV syncytia formation on cells

Results and discussion: CDV-PEDV-spike-MUT recombinant showed higher infectious virus titers on day 1, 2, 3, 4, 5 and 6 after infection of Vero cells. Furthermore, both recombinants reached peak supernatant titers on day 4 post infection, but CDV-PEDV-spike-MUT reached 2-fold higher infection titers than CDV-PEDV-spike-WT recombinant (see FIG. 2), indicating the benefits of the mutation of the spike to the fitness of the CDV vector.

All those virus titers were measured in cell free supernatants. Based on empirical data (data not shown) it is expected that the titers in the cell fractions are at least 100 times higher, and that thus in a production setup (as the roller bottles would be harvested including the cell fraction in the production setup) the titer differences between the two recombinants are proportionally even higher.

Example 4 Vaccine Animal Data Vaccine Efficacy Study

Porcine epidemic diarrhea (PED) is a highly contagious swine disease that can have tremendous economic impact. While all age classes of pigs are susceptible to infection, severe clinical signs and mortality are mainly seen in suckling piglets. The causative agent is PED virus (PEDV), an enveloped, single positive-stranded RNA-virus of the genus Alphacoronavirus within the Coronaviridae virus family. In Europe, PEDV first occurred in the late 1970ies in England. Afterwards it spread through whole Europe causing sporadic outbreaks. In the late 1990ies, PEDV had disappeared from the European pig farms as evidenced by very low seroprevalence and non-existent disease reporting. Outbreaks and endemic infections were still reported from Asia where the disease has high impact on the productivity of industrialized pig farms. Starting from 2005, PED cases were again reported from Europe, i.e. Italy. After the introduction of an apparently highly virulent PEDV into the United States in 2013, cases were also reported from Central Europe, including Germany and neighboring countries. The latter cases were caused by related but distinct PEDV strains (so-called S-INDEL strains). In Germany, cases were reported starting from May 2014 with high morbidity and variable lethality in suckling pigs.

This study, in which a CDV backbone derived from Lederle vaccine strain (c.f. Example 1) with an insert of the sequence of SEQ ID NO:37 (encoding a PEDV Spike protein) between the P gene and the M gene (the vector thus comprising the sequence of SEQ ID NO:38) was tested as vector vaccine (named hereinafter “CDV_PEDV-Spike vaccine” or “CDV PEDV-Spike vector vaccine”, respectively), included six sows and their offspring.

All animals were checked for PEDV by RT-qPCR targeting the S-gene, and PEDV-specific antibodies. Only negative animals were enrolled in the study.

Three treatment groups (see below) received randomly assigned animals:

Group 1 (negative control): Two sows (designated #1 and #2), unvaccinated;

Group 2 (positive control): Two sows (designated #3 and #4), unvaccinated;

Group 3 (CDV_PEDV-Spike): Two sows (designated #5 and #6), vaccinated with CDV PEDV-Spike vector vaccine.

The vaccination of the two sows of group 3 was done according to the following scheme, wherein the stock titer of the CDV_PEDV-Spike vaccine, defined by endpoint titration, was 7.94×10⁴ TCID₅₀/ml:

9 weeks prior to expected farrowing date: each of the two sows received 4 ml of the vaccine intranasally (2 ml in each nostril);

6 weeks prior to expected farrowing date: each of the two sows received 4 ml of the vaccine intranasally (2 ml in each nostril);

3 weeks prior to expected farrowing date: each of the two sows received 4 ml of the respective vaccine intranasally (2 ml in each nostril) and additionally 2 ml intramuscularly.

Piglets born to sows of group 1 (13 piglets of sow #1 and 12 piglets of sow #2) were orally mock-inoculated. Piglets born to sows of group 2 (12 piglets of sow #3 and 14 piglets of sow #4), and group 3 (5 piglets of sow #5 and 15 piglets of sow #6) were orally challenged with a PEDV field strain (named “PEDV EU” hereinafter) at an age of 4 days of life.

For inoculation of piglets of groups 2 and 3, cell culture adapted PEDV EU was used. The titer was 2.15×10⁵ TCID₅₀/ml. Piglets of groups 2 and 3 were orally inoculated. In this case, each piglet received 1 ml of a 1:10 diluted viral stock (titer 2.15×10⁴ TCID₅₀) using 2 ml syringes.

Piglets of group 1 were orally mock-inoculated using 1 ml cell culture medium in 2 ml syringes.

During the whole trial, rectal swabs (COPAN plain swabs without medium) were taken at the day of inoculation and on day 1 to 10 post inoculation (pi) as well as day 14, 17 and 20/21 pi of all animals for RT-qPCR analyses. Additional rectal swabs were taken from 4 piglets of each sow prior to inoculation and two days post challenge for bacteriological examination. Moreover, clinical signs indicative for PED were recorded daily using the established standardized cumulative score system (see below). Blood samples were taken at the day of inoculation and day 14 and 20/21 pi (end of trial) or the day of euthanasia or death of the respective animal.

Clinical Monitoring

The established cumulative clinical score was used for daily monitoring for clinical signs indicative for PED (see table below).

TABLE 1 Cumulative clinical score for clinical signs indicative for PED Gastrointestinal Score General behaviour Feed intake/suckling symptoms 0 Agile, attentive, no Greedy suckling, good Physiological feces abnormalities filled stomach, intake of piglet feed 1 Slight depression Slow suckling, hardly Pasty feces, vomiting interested in piglet feed 2 Depression, isolaton from Reluctant feed intake, Watery feces, reddened group, vocalisation hardly interested in anal region, vomiting (moaning) suckling/piglet feed, sunken flanks 3 Lateral position, signs of Total anorexia, Watery feces with blood severe dehydration, low decreasing of milk or fibrin added, highly body temperature production of sow reddened anal region, vomiting

Sample Preparation and Nucleic Acid Extraction

Rectal swabs were submerged in 1 ml Dulbecco's Modified Eagle Medium and incubated for 1 hour at room temperature. Viral RNA was extracted using either the QIAmp ViralRNA Mini Kit (Qiagen) or the NucleoMagVet-Kit in combination with the KingFisher extraction platform. The RNA was stored at −20° degree until further use.

Blood samples were centrifuged at 2031×g for 20 min at room temperature to obtain serum. The resulting serum was aliquoted and stored at −20° C.

Virus Detection

To detect PEDV shedding, RT-qPCR-systems targeting the S-gene of PEDV were used as previously described (Stadler et al., BMC Vet Res. 11:142 (2015)). Samples taken at days 0 to 7 dpi (days post challenge virus inoculation) and at 10 and 20/21 dpi were tested for PEDV-genome. The amount of genome copies/μl was calculated using an in-house standard.

Antibody Detection

A commercial indirect ELISA (INgezim PEDV, INGENASA, Madrid, Spain) was performed with all sera according to the producer's manual.

Bacteriology

Fecal swabs of four piglets per litter were taken at 0 and 2 dpi for differential bacteriology.

Statistics

Shapiro-Wilk test was used for normality testing and a Mann-Whitney rank sum test was conducted as implemented in the software package. Statistical significance was tested using SigmaPlot software.

Results Antibody Detection in Serum

All piglets of the CDV group showed positive results in the ELISA (detecting antibodies against PEDV Spike protein) prior to challenge inoculation due to antibody positive colostrum intake, while all animals of the positive and negative control group showed clearly negative results.

At 14 dpi all but three piglets in the positive control group seroconverted, while all animals in the vaccine group showed still high amounts of PEDV specific IgG in serum samples.

At the end of the study all piglets of the CDV group and of the positive control group showed strongly positive results in the ELISA. None of the animals in the negative control seroconverted during the whole trial.

In a further study it was also seen that respective antibody results were likewise achieved when the mother sows were only vaccinated twice via the intranasal route.

Bacteriology

Fecal swabs taken at 0 and 2 dpi did not show any pathogenic bacteria. The bacterial flora did not undergo significant changes upon infection.

Clinical Signs

Piglets of the positive control group (group 2) clearly showed clinical signs indicative for PEDV over 7 days starting with vomiting 24 hpi followed by diarrhea. 8 of 26 of the piglets had to be euthanized due to severe dehydration and clinical score values over 6 (humane endpoint). First clinical signs indicative for PEDV were detectable at 36 hpi.

In total, the clinical signs of the CDV vector vaccinated and PEDV challenged piglets (group 3) were better regarding the general behavior and only 2 of 20 (10%) of the pigs of group 3 had to be euthanized due to severe dehydration and clinical score values over 6 (as compared to 31% of the piglets of group 2).

Animals in the negative control stayed healthy during the whole trial.

Shedding of Virus

A clear difference in virus shedding could be detected between the challenged groups. At 1 dpi all challenged piglets were positive for virus genome in rectal swabs, but animals in the CDV-PEDV vaccinated group showed significantly lower PEDV genome copy numbers (mean CT value 32.79), then in challenge group (mean CT value 26.65).

Also, while for the next five days pi, the genome load in rectal swabs of the CDV group was quite similar to the positive control, beginning at 7 dpi the detectable amount of virus genome declined below the cutoff level in piglets protected by the vaccinated sows, while all animals in the positive control group still shed PEDV.

No PEDV genome could be detected in swabs of the negative control group.

In conclusion, the outcome of the study was that piglets born to sows vaccinated with the CDV PEDV-Spike recombinant vaccine showed a reduction of clinical signs, as compared to the positive control, and in particular, a great improvement was seen with regard to the mortality/letality of the piglets. Furthermore, virus shedding after the PEDV challenge was significantly reduced.

Besides, an animal study corresponding to the above described vaccine efficacy study is performed, wherein a CDV backbone derived from Lederle vaccine strain (c.f. Example 1) with an insert encoding the PEDV Spike protein of SEQ ID NO:40 between the P gene and the M gene is administered twice (5 weeks prior to farrowing and 2 weeks prior to farrowing), and wherein a highly virulent genotype 2a PEDV field strain is used for the challenge. Piglets born to sows vaccinated with this recombinant vaccine show reduced mortality or a reduction of clinical signs, as compared to the challenge control.

EXAMPLE 5

This animal study, in which a CDV backbone derived from Lederle vaccine strain (c.f. Examples 1 and 4) with an insert encoding the PEDV Spike protein of SEQ ID NO:20 between the P gene and the M gene was tested as vector vaccine (named hereinafter “CDV PEDV-G2a vaccine” or “CDV PEDV-G2a Spike vector vaccine”, respectively), included twenty (20) sows and their offspring.

Only animals which were considered negative for PEDV by qRT-PCR and ELISA were enrolled in the study.

Three treatment groups (see below) received randomly assigned animals:

Group 1 (Strict negative control): Four sows (designated 1-4), unvaccinated;

Group 2 (Challenge control): Eight sows (designated 5-12), unvaccinated;

Group 3 (CDV_PEDV-G2a-Spike): Eight sows (designated 13-20), vaccinated with CDV PEDV-G2a-Spike vector vaccine.

The vaccination of the 8 sows of group 3 was done at 5 weeks pre-farrow (DO) and 2 weeks pre-farrow (D21) of the study, wherein the stock titer of the CDV PEDV-G2a Spike vaccine, defined by endpoint titration, was 2.57×10⁵ TCID50/ml. At each vaccination, the sows received 4 mL of the vaccine intranasally (2 mL in each nostril).

Piglets born to sows of group 1 (41 piglets in total) were not challenged (strict controls). Piglets born to sows of group 2 (81 piglets in total), and group 3 (83 piglets in total) were orally challenged with a highly virulent PEDV field strain belonging to G2a genotype with the dose 2.0×10³ TCID₅₀/2 mL dose (1 mL intranasal+1 mL oral) at an age of 3-7 days of life.

During the whole trial, rectal swabs were taken at the day prior to inoculation and on day 1, 3, 7 and 14 pi (post challenge virus inoculation).

Sample Preparation and Nucleic Acid Extraction

Rectal swabs were submerged in 2 ml Minimum Essential Medium (MEM) upon collection and stored at −70° C. prior to processing. Sample were processed by vortexing for 10 seconds followed by centrifugation for 10 minutes at 1,500×g at 4° C. Following processing, 100 μl/sample was used for viral RNA extraction using the BS96 Vet 100 BioSprint extraction platform with the BioSprint One-For-All Vet Kit (Qiagen) The RNA was stored at −20° degree until further use.

Blood samples were centrifuged at 1960×g for 10 min at room temperature to obtain serum. The resulting serum was aliquoted and stored at −70° C.

Virus Detection

To detect PEDV shedding, an internally derived RT-qPCR-system targeting the S-gene of PEDV was used: The quantitative one-step RT-PCR kit (iTaq Universal One-Step RT-PCR kit; BioRad, cat no. 1725140) was used for the assay. Real-time RT-PCR was carried out in a 25 μl reaction containing 2 μl of extracted total nucleic acid, 0.75 μl of probe (4 μM), 0.5 μl of each primer (10 μM), 12.5 μl of 2X RT-PCR mix, 0.5 μl iScript reverse transcriptase and 8.25 μl of DEPC-treated water. See Table 2 below for primer, probe and ultramer sequences. The reaction took place using a CFX96 real-time PCR detection system (BioRad) under the following conditions: initial reverse transcription at 50° C. for 30min, followed by initial denaturation at 95° C. for 5 min, 40 cycles of denaturation at 95° C. for 15 s and annealing and extension at 57° C. for 30 s. To generate quantitative data, a PEDV ultramer was included in each run (Integrated DNA Technologies). The lyophilized ultramer (4 nmol) was resuspended in DEPC-treated, nuclease-free sterile water to generate a stock concentration of 1.0E+10 genomic copies per μl (gc/μl). From the stock ultramer, 10 fold serial dilutions from 1.0E+08 to 1.0E+01 were made in the DEPC-treated water. The concentration was confirmed by qubit dsDNA HS Assay prior to use. The optical data were analyzed using CFX Manager software. For each determination, the threshold lines were automatically calculated using the regression setting for cycle threshold (Ct) determination mode. Baseline subtraction was done automatically using the baseline subtracted mode. Curves with baseline end values of less than 10 were manually corrected.

TABLE 2 Probe (Pr), primer (F/R), and ultramer sequences used for the internally derived RT-qPCR-system. Probe/primer name Sequence 0086-001-1 Pr 56-FAM/ACAGAGCCTGTGTTGGTGTATAGTAACAT/3BHQ_1 (SEQ ID NO: 41) 0089-065-1 F TATAGTGGGTGTTATTTCTAGTT (SEQ ID NO: 42) 0086-001-2 R GCCAATACTGCCAGATTTACA (SEQ ID NO: 43) PEDV-ultramer 5′/TGATGATATAGTGGGTGTTATTTCTAGTTTGTCTAGCTCCACTT TTAACAGTACTAGGGAGTTGCCTGGTTTCTTCTACCATTCTAATG ATGGCTCTAATTGTACAGAGCCTGTGTTGGTGTATAGTAACATAG GTGTTTGTAAATCTGGCAGTATTGGCTATGTCCCAT/3′ (SEQ ID NO: 44)

Antibody Detection

An in house developed CCIF assay was used to test serum and milk samples from this study: A wild-type PEDV isolate (Genogroup 2a) was diluted 1:100 into PEDV growth media (MEM+2.5% HEPES+0.3% Tryptose phosphate broth+0.02% yeast+10 μg/mL trypsin). The diluted virus (100 μL/well) was inoculated onto two-day old 96-well plates planted with VERO cells. Prior to infection, cell growth media was removed from the plates and they were washed twice with 100 μL of PEDV growth media. Plates were incubated for 24 hours at 37±2° C.+CO2 (4-6%). Following incubation, the supernatant was discarded and plates were washed twice with 200μL/well 1×PBS. For fixation, 200 μL/well of Ethanol was added. Plates were incubated at room temperature for 30 minutes, air-dried, then stored at −20° C. until use. Prior to use in the assay, plates were rehydrated with 200 μl well 1×PBS (Gibco) for 10 min at room temperature and blocked with 100 μl/well buffer (1×PBS+1% normal goat serum+0.1% triton X) for 15 minutes at 37° C. Serial two-fold dilutions of serum samples were prepared in a dilution buffer (1×PBS+5% BSA+1% normal goat serum+0.1% titron-X 100) containing a 1:1000 dilution of PEDV Mab antibody (Median diagnostics). Diluted samples (50 μl/well) were added to the prepared plates and incubated at 37° C. for 1 hour. Following incubation, plates were washed three times with 200 μl/well 1×PBS. A total of 50 μl/well of diluted secondary antibodies [Alexa594 goat anti-mouse IgG (Fisher, 1:500 dilution); FITC labeled, goat anti-pig IgG (BioRad, 1:500 dilution); Hoechst 33342 (Fisher, 1:1000 dilution)] was then added to each plate and incubated at 37° C. for 1 hour. Following incubation, plates were washed three times with 200 μl/well 1×PBS. Fluorescence was observed where PEDV-infected cells bound by Mab3F12 showed specific red fluorescence. Co-localization of green fluorescence indicated binding of pig IgG. The highest dilution where specific green fluorescence was detected was equivalent to the IgG titer.

Results Mortalities

In group 1 (strict control) 40 pigs survived, in group 2 (challenge control) 16 pigs survived, and in group 3 (CDV-PEDV-G2a spike vaccinated) 34 pigs survived, resulting in an average mortality of 2% (group 1), 80% (group 2), and 59% (group 3), respectively.

Antibody Response

Specific PEDV antibody response after challenge revealed that the mean levels of CCIF IgG antibody titers in the sow sera and milk were higher in the CDV-PEDV-G2a spike vaccinated group than in group 2 (challenge control). This indicates that the vaccinated sows were strongly responding by boosting the IgG levels in milk and sera after contracting the virus from infected piglets post challenge. In comparison to this, the antibody titers of the sows of the challenge control, merely resulting from PEDV infection through contact with the challenged piglets (and their feces), were significantly lower.

Shedding of Virus

On day 3 post challenge virus inoculation, relatively similar mean RNA loads were detected in the vaccinated and non-vaccinated group, reaching 9,2 and 9,8 group mean log10 PEDV genomic copies for the CDV-PEDV-G2a spike vaccinated group and the challenge control group, respectively. On D48 (7 dpi) and D55 (14 dpi), the mean log10 PEDV genomic copy number in the CDV-PEDV-G2a spike vaccinated group were 3.2 and 2.0 logs10, respectively, while in the challenge control group were 5.5 and 3.9 logs 10, respectively, indicating the reduction of 2.3 and 1.9 logs on days 7 and 14 pi, respectively. Although no longer term monitoring of shedding has been performed, the tendency of dynamics of shedding observed on days 7 and 14 post challenge virus inoculation clearly indicates a shortened shedding time in the vaccinated animals in accordance with the results as described above under Example 4.

No PEDV genome could be detected in swabs of the strict negative control group.

In conclusion, the outcome of the study was that piglets born by or, respectively, suckled by sows vaccinated with the CDV PEDV-G2a spike recombinant vaccine showed a significant reduction of mortality, as compared to the piglets of the control group, when challenged with a highly virulent PEDV strain. Also, these piglets receiving PEDV protective IgG antibodies from milk, via transfer of maternal antibodies in the initial days post partum, revealed a significant reduction of virus shedding post challenge, which is an important epidemiological parameter, on days 7 and 14 post infection. 

What is claimed is:
 1. A nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein selected from the group consisting of the following (a) and (b): (a) a genotype 2a (G2a) PEDV S protein having at least one mutation, wherein the leucine residue at amino acid position 900 is substituted by an amino acid residue other than a leucine residue, and/or the leucine residue at amino acid position 901 is substituted by an amino acid residue other than a leucine residue, wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2a PEDV S protein of SEQ ID NO:2 or SEQ ID NO:39; (b) a genotype 2b (G2b) PEDV S protein having at least one mutation, wherein the leucine residue at amino acid position 897 is substituted by an amino acid residue other than a leucine residue, and/or the leucine residue at amino acid position 898 is substituted by an amino acid residue other than a leucine residue, wherein the numbering of the amino acid positions refers to the amino acid sequence of wild type G2b PEDV S protein of SEQ ID NO:3.
 2. The nucleic acid molecule of claim 1, wherein said amino acid residue other than a leucine residue is selected from the group consisting of alanine residue, glycine residue, isoleucine residue, methionine residue and valine residue.
 3. The nucleic acid molecule of claim 1 or 2, wherein the numbering of the amino acid positions refer to the amino acid sequence RSXIEDLLF (SEQ ID NO:4) of wild type G PEDV S protein, wherein R is the conserved arginine residue of the S1/S2 cleavage site and LL are the amino acid positions 900 and 901 within the genotype 2a (G2a) PEDV S protein or LL are the amino acid positions 897 and 898 within the genotype 2b (G2b) PEDV S protein.
 4. A nucleic acid molecule encoding a porcine epidemic diarrhea virus (PEDV) spike (S) protein comprising the amino acid sequence (SEQ ID NO: 1) RSX₁IEDX ₂ X ₃,

wherein R is the conserved arginine residue of the S1/S2 cleavage site of said PEDV S protein, X₁ can be any amino acid residue, and wherein (I) X₂ is an amino acid residue other than a leucine residue and X₃ is a leucine residue, or (II) X₂ is a leucine residue and X₃ is an amino acid residue other than a leucine residue, or (III) X₂ is an amino acid residue other than a leucine residue and X₃ is an amino acid residue other than a leucine residue.
 5. The nucleic acid molecule of any one of claims 1 to 4, wherein said PEDV S protein comprises the amino acid sequence RSXIEDAAF (SEQ ID NO:5), wherein R is the conserved arginine residue of the Sl/S2 cleavage site of said PEDV S protein and AA are the amino acid positions 900 and 901 within the genotype 2a (G2a) PEDV S protein or AA are the amino acid positions 897 and 898 within the genotype 2b (G2b) PEDV S protein.
 6. The nucleic acid molecule of any one of claims 1 to 5, wherein said PEDV S protein further comprises the amino acid sequence (SEQ ID NO: 6) X ₁X₂X₃FX₄KX₅ X ₆X₇X₈,

wherein X₈ is the C-terminal amino acid residue of said PEDV S protein or the amino acid residue at the −2 position relative to the C-terminal amino acid position of said PEDV S protein, X₂ to X₅, X₇ and X₈ can be any amino acid residue, and wherein (i) X₁ is an amino acid residue other than a tyrosine residue and X₆ is a histidine residue, or (ii) X₁ is a tyrosine residue and X₆ is an amino acid residue other than a histidine residue, or (iii) X₁ is an amino acid residue other than a tyrosine residue and X₆ is an amino acid residue other than a histidine residue.
 7. The nucleic acid molecule of any one of claim 1 to 3, 5 or 6, wherein (a) in said G2a PEDV S protein further the tyrosine residue at amino acid position 1377 is substituted by an amino acid residue other than a tyrosine residue, and/or the histidine residue at amino acid position 1384 is substituted by an amino acid residue other than a histidine residue, or (b) in said G2b PEDV S protein further the tyrosine residue at amino acid position 1374 is substituted by an amino acid residue other than a tyrosine residue, and/or the histidine residue at amino acid position 1381 is substituted by an amino acid residue other than a histidine residue.
 8. The nucleic acid molecule of claim 6 or 7, wherein said amino acid residue other than a tyrosine residue is selected from the group consisting of alanine residue, glycine residue, leucine residue, isoleucine residue, methionine residue and valine residue, and/or said amino acid residue other than a histidine residue is an arginine residue.
 9. The nucleic acid molecule of any one of claims 1 to 8, wherein said PEDV S protein: i) (a) comprises or consists of an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 15, 16, 17, 18, 19, 20, 40, or (b) comprises or consists of an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 9, 10, 11, 12, 13, 14; and/or ii) (a) is encoded by a nucleotide sequence encoding an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence any one of SEQ ID NOs: 15, 16, 17, 18, 19, 20, 40, or (b) is encoded by a nucleotide sequence encoding an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% sequence identity with the amino acid sequence of any one of SEQ ID NOS: 9, 10, 11, 12, 13,
 14. 10. A PEDV (S) protein encoded by the nucleic acid molecule of any one of claims 1 to
 9. 11. The nucleic acid molecule of any one of claims 1 to 9 or the PEDV S protein of claim 10, wherein said nucleic acid molecule encoding the PEDV S protein or the PEDV S protein is recombinant.
 12. A vector comprising the nucleic acid molecule of any one of claims 1 to
 9. 13. An immunogenic composition comprising the nucleic acid molecule encoding the PEDV S protein of any one of claims 1 to 9 and/or the PEDV S protein of claim 10 and/or the vector of claim
 12. 14. A method of immunizing a subject comprising administering to the subject an immunogenic composition of claim
 13. 15. A method of reducing or preventing the clinical signs or disease caused by an infection with a PEDV in a piglet, wherein the piglet is to be suckled by a sow to which the immunogenic composition of claim 13 has been administered.
 16. A method of reducing the mortality caused by an infection with a PEDV in a piglet, wherein the piglet is to be suckled by a sow to which the immunogenic composition of claim 12 has been administered.
 17. The method of any one of claims 14 to 16, wherein said immunogenic composition is administered intranasal, mucosal, oral, intradermal or intramuscular. 